What would be a more effective analytical technique to use other than colorimetry to determine concentration?
Q. Colorimetry is a analytical technique used to determine the concentration of a solution. I recently did a colorimetric analysis to find the concentration of phorsphorus of a sample of fertiliser, the answer was not very accurate (because the human eyes were used to compare the colour of the sample to the colour of the standard solutions). Just wondering what other techniques can be used next time to obtain more accurate results for this type of prac? Thanks
Asked by Helen O - Wed Apr 30 07:06:58 2008 - - 1 Answers - 0 Comments
A. Usually you would use titration techniques with proper indicators. Colorimetry is nowadays only used when done by photometry, i.e. an electronic device measuring one specific wave length very accurately and automatically. The human eye is not a good analytical detector...
Answered by Kajjo - Wed Apr 30 07:10:42 2008
Q. Colorimetry is a analytical technique used to determine the concentration of a solution. I recently did a colorimetric analysis to find the concentration of phorsphorus of a sample of fertiliser, the answer was not very accurate (because the human eyes were used to compare the colour of the sample to the colour of the standard solutions). Just wondering what other techniques can be used next time to obtain more accurate results for this type of prac? Thanks
Asked by Helen O - Wed Apr 30 07:06:58 2008 - - 1 Answers - 0 Comments
A. Usually you would use titration techniques with proper indicators. Colorimetry is nowadays only used when done by photometry, i.e. an electronic device measuring one specific wave length very accurately and automatically. The human eye is not a good analytical detector...
Answered by Kajjo - Wed Apr 30 07:10:42 2008
how does the standard deviation help u to determine concentration of data n whether there r potential outliers?
Q. how does the standard deviation help you to determine concentration of data and whether there are potential outliers?
Asked by xxTxx - Mon Oct 6 01:26:42 2008 - - 1 Answers - 0 Comments
A. Ok Remeber that the sd is a measure of the dispersion of your scores. Think of your bell curve. 68 percent of your values will fall +/- 1 sd from the mean. A larger sd usually clues you in on the fact that the distribution of the data is skewed or has a measure of kurtosis. A positive or negative skew can be an indication of outlliers in the sample
Answered by dopeydope98 - Mon Oct 6 03:01:06 2008
Q. how does the standard deviation help you to determine concentration of data and whether there are potential outliers?
Asked by xxTxx - Mon Oct 6 01:26:42 2008 - - 1 Answers - 0 Comments
A. Ok Remeber that the sd is a measure of the dispersion of your scores. Think of your bell curve. 68 percent of your values will fall +/- 1 sd from the mean. A larger sd usually clues you in on the fact that the distribution of the data is skewed or has a measure of kurtosis. A positive or negative skew can be an indication of outlliers in the sample
Answered by dopeydope98 - Mon Oct 6 03:01:06 2008
Why concentration cannot be determined?
Q. What are two reasons why the concentration of a sodium hydroxide solution cannot be determined accurately from the preparation of the solution, even if one is very careful in measuring the mass of sodium hydroxide and the volume of the solution.
Asked by Matt K - Tue Oct 14 23:07:19 2008 - - 2 Answers - 0 Comments
A. if the conc of NaOH is sufficiently high, and if the solution is not sealed and open to the atmosphere, it will absorb both water and carbon dioxide from the air and its concentration and characteristics will change accordingly.
Answered by Ja Ma - Tue Oct 14 23:15:08 2008
Q. What are two reasons why the concentration of a sodium hydroxide solution cannot be determined accurately from the preparation of the solution, even if one is very careful in measuring the mass of sodium hydroxide and the volume of the solution.
Asked by Matt K - Tue Oct 14 23:07:19 2008 - - 2 Answers - 0 Comments
A. if the conc of NaOH is sufficiently high, and if the solution is not sealed and open to the atmosphere, it will absorb both water and carbon dioxide from the air and its concentration and characteristics will change accordingly.
Answered by Ja Ma - Tue Oct 14 23:15:08 2008
How is the concentration of a buffer solution determined?
Q. How is the concentration of a buffer solution determined?
Asked by charm - Sat Dec 1 01:50:21 2007 - - 3 Answers - 0 Comments
A. You need to refine your question. A buffer is actually a mixture of two species: a weak acid and its conjugate base, so there are actually two concentrations that contribute to the pH of a buffer. A buffer is a solution that has a relatively constant pH over a wide range of added acid or base. You may want to check out the Henderson-Hasselbalch equation. It is used to compute the pH of a buffer based on the concentrations of weak acid and conjugate base and the Ka for the weak acid.
Answered by pisgahchemist - Sat Dec 1 02:18:02 2007
Q. How is the concentration of a buffer solution determined?
Asked by charm - Sat Dec 1 01:50:21 2007 - - 3 Answers - 0 Comments
A. You need to refine your question. A buffer is actually a mixture of two species: a weak acid and its conjugate base, so there are actually two concentrations that contribute to the pH of a buffer. A buffer is a solution that has a relatively constant pH over a wide range of added acid or base. You may want to check out the Henderson-Hasselbalch equation. It is used to compute the pH of a buffer based on the concentrations of weak acid and conjugate base and the Ka for the weak acid.
Answered by pisgahchemist - Sat Dec 1 02:18:02 2007
How can the Beer Lambert Law be used to determine the concentration of a substance in solution?
Q. If you know the molar absorbance coefficient of a particular substance, how can the Beer-Lambert Law be used to determine the concentration of a substance in solution?
Asked by heartybarbeque - Thu Apr 24 04:23:08 2008 - - 1 Answers - 0 Comments
A. Beer Lambert Law: A=E.b.c You have the the solution...measure its absorbance(A), you know the absorbace coefficient(E), you know the path length of the cell used to measure absorbance(b). Now rearrange the equation to get c... c = A/(E.b) done kthnx
Answered by minip2087 - Thu Apr 24 04:30:25 2008
Q. If you know the molar absorbance coefficient of a particular substance, how can the Beer-Lambert Law be used to determine the concentration of a substance in solution?
Asked by heartybarbeque - Thu Apr 24 04:23:08 2008 - - 1 Answers - 0 Comments
A. Beer Lambert Law: A=E.b.c You have the the solution...measure its absorbance(A), you know the absorbace coefficient(E), you know the path length of the cell used to measure absorbance(b). Now rearrange the equation to get c... c = A/(E.b) done kthnx
Answered by minip2087 - Thu Apr 24 04:30:25 2008
What is the point of determining DNA concentration?
Q. In lab class today we determined DNA concentration by using a UV spec. Just wanted to understand why DNA concentration is important.
Asked by greydonthemagician - Tue Sep 30 18:14:04 2008 - - 2 Answers - 0 Comments
A. In molecular biology, you need to know the concentration of DNA and RNA all the time. There are experiments that use DNA sources as substrates and you need to equalize the concentration of all your samples to the same amount of substrate, hence you need to know their concentration! Also, some reactions, such as bacteria transformation (that process that inserts heterologous DNA into a bacterium) are inhibited by too much DNA, therefore you need to know how much you are using. Among the experiments in which you need the quantification of DNA and RNA are: PCR reaction (polymerase chain reaction) Southern blot (running of DNA onto a gel, transferring onto a membrane and staining it with a specific radiolabeled or chemoluminescent ptobe.… [cont.]
Answered by Red Head Angel - Tue Sep 30 18:29:05 2008
Q. In lab class today we determined DNA concentration by using a UV spec. Just wanted to understand why DNA concentration is important.
Asked by greydonthemagician - Tue Sep 30 18:14:04 2008 - - 2 Answers - 0 Comments
A. In molecular biology, you need to know the concentration of DNA and RNA all the time. There are experiments that use DNA sources as substrates and you need to equalize the concentration of all your samples to the same amount of substrate, hence you need to know their concentration! Also, some reactions, such as bacteria transformation (that process that inserts heterologous DNA into a bacterium) are inhibited by too much DNA, therefore you need to know how much you are using. Among the experiments in which you need the quantification of DNA and RNA are: PCR reaction (polymerase chain reaction) Southern blot (running of DNA onto a gel, transferring onto a membrane and staining it with a specific radiolabeled or chemoluminescent ptobe.… [cont.]
Answered by Red Head Angel - Tue Sep 30 18:29:05 2008
How to determine the concentration of an unknown acid?
Q. As the title says, how does one determine the concentration of an unknown acid (i am not given any info about it), without the use of pipettes, burettes or such equipment
Asked by lord_equilibrium - Fri Feb 27 08:10:57 2009 - - 2 Answers - 0 Comments
A. assuming the acid is monoprotic ( contains only one acidic hydrogen ) then place a known volume of the acid solution in a flask add an indicator like phenolphthalein and then from a burette add slowly a sodium hydroxide solution of known concentration ( such as 0.1 N or M) until there is a permanent pink in the solution. The indicator phenolphthalein will change from colorless to pink at pH ~ 8.2 and is uite red at pH 9. The first permanent pink tells you that you are very near the equivalence point..that is the place at which the amount of added base is exactly equal to the amount of acid present. Then determine the concentration this way vol base x N(M) base = mmoles of base at equivalence point ( the indicator assessed point )… [cont.]
Answered by Merlin's Feline - Fri Feb 27 09:22:58 2009
Q. As the title says, how does one determine the concentration of an unknown acid (i am not given any info about it), without the use of pipettes, burettes or such equipment
Asked by lord_equilibrium - Fri Feb 27 08:10:57 2009 - - 2 Answers - 0 Comments
A. assuming the acid is monoprotic ( contains only one acidic hydrogen ) then place a known volume of the acid solution in a flask add an indicator like phenolphthalein and then from a burette add slowly a sodium hydroxide solution of known concentration ( such as 0.1 N or M) until there is a permanent pink in the solution. The indicator phenolphthalein will change from colorless to pink at pH ~ 8.2 and is uite red at pH 9. The first permanent pink tells you that you are very near the equivalence point..that is the place at which the amount of added base is exactly equal to the amount of acid present. Then determine the concentration this way vol base x N(M) base = mmoles of base at equivalence point ( the indicator assessed point )… [cont.]
Answered by Merlin's Feline - Fri Feb 27 09:22:58 2009
A student wishes to determine the concentration of a solution of HCl.?
Q. A student wishes to determine the concentration of a solution of HCl. The student adds 10.00 mL of the HCl solution to 150 mL of water, adds an indicator, and titrates with .0965 M NaOH. If the titration requires 32.45 mL of base, what is the concentartion of the HCl solution?
Asked by EE - Sun Aug 26 16:21:15 2007 - - 1 Answers - 0 Comments
A. 10 mL x M = 32.45 mL x 0.0965 HCl = 0.3131 M
Answered by skipper - Sun Aug 26 16:55:37 2007
Q. A student wishes to determine the concentration of a solution of HCl. The student adds 10.00 mL of the HCl solution to 150 mL of water, adds an indicator, and titrates with .0965 M NaOH. If the titration requires 32.45 mL of base, what is the concentartion of the HCl solution?
Asked by EE - Sun Aug 26 16:21:15 2007 - - 1 Answers - 0 Comments
A. 10 mL x M = 32.45 mL x 0.0965 HCl = 0.3131 M
Answered by skipper - Sun Aug 26 16:55:37 2007
How do i determine the concentration of triiodide ions in solution?
Q. I am reacting potassium iodide and iodine solid. I know I will get some iodide ions and some triiodide ions, so how do i determine the concentrations of each? and is it possible to remove the iodide ions?
Asked by nonomomowo - Sun Aug 24 00:34:23 2008 - - 1 Answers - 0 Comments
A. Triiodide reacts with starch to give a colored material. titrate it. Look up starch-iodide titration.
Answered by odimwitdwon - Sun Aug 24 00:46:04 2008
Q. I am reacting potassium iodide and iodine solid. I know I will get some iodide ions and some triiodide ions, so how do i determine the concentrations of each? and is it possible to remove the iodide ions?
Asked by nonomomowo - Sun Aug 24 00:34:23 2008 - - 1 Answers - 0 Comments
A. Triiodide reacts with starch to give a colored material. titrate it. Look up starch-iodide titration.
Answered by odimwitdwon - Sun Aug 24 00:46:04 2008
how is the free alkali and free alkali + carbonate concentration determined in soap making?
Q. how is the free alkali and free alkali + carbonate concentration determined in soap making?
Asked by el nams - Sat Dec 16 06:58:12 2006 - - 1 Answers - 0 Comments
A. These are usually measured from samples in the final product and not from the mother liquid of the batch of soap made. With fresh ingredients, no carbonate is usually found. The free alkali is used to estimate possible skin irritation. A small, measured amount of soap is totally dissolved in warm water and then allowed to cool to room temperature. The free alkali plus carbonate is usually determined by volumetric titration with a known acid solution. The carbonate is not an added ingredient, but is usually present in small amounts from the reaction of the alkali with Carbon dioxide in the air. The carbonate can also be removed using Barium nitrate and the resulting solution is filtered and then used to determine the free alkali. … [cont.]
Answered by Richard - Sun Dec 17 10:13:04 2006
Q. how is the free alkali and free alkali + carbonate concentration determined in soap making?
Asked by el nams - Sat Dec 16 06:58:12 2006 - - 1 Answers - 0 Comments
A. These are usually measured from samples in the final product and not from the mother liquid of the batch of soap made. With fresh ingredients, no carbonate is usually found. The free alkali is used to estimate possible skin irritation. A small, measured amount of soap is totally dissolved in warm water and then allowed to cool to room temperature. The free alkali plus carbonate is usually determined by volumetric titration with a known acid solution. The carbonate is not an added ingredient, but is usually present in small amounts from the reaction of the alkali with Carbon dioxide in the air. The carbonate can also be removed using Barium nitrate and the resulting solution is filtered and then used to determine the free alkali. … [cont.]
Answered by Richard - Sun Dec 17 10:13:04 2006
The concentration of a hydrogen peroxide solution can be conveniently determined?
Q. by titration against a standardized potassium permanganate solution in an acidic medium according to the following equation: 2 MnO4- + 5 H2O2 + 6 H+ 5 O2 + 2 Mn2+ + 8 H2O If 36.44 mL of a 0.01652 M KMnO4 solution are required to completely oxidize 25.00 mL of a H2O2 solution, calculate the molarity of the H2O2 solution.
Asked by cheergurliej11 - Tue Feb 12 00:06:38 2008 - - 1 Answers - 0 Comments
A. moles MnO4- = 0.01652 x 0.03644 = 0.0006020 mol have 5/2 = 2.5 x 0.0006020 = 0.001505 mol H2O2 Vol = 36.44ml + 25.00ml = 61.44 ml Molarity = 0.001505 / 0.06144 = 0.02450 mol /L, H2O2
Answered by Michael E - Tue Feb 12 00:15:29 2008
Q. by titration against a standardized potassium permanganate solution in an acidic medium according to the following equation: 2 MnO4- + 5 H2O2 + 6 H+ 5 O2 + 2 Mn2+ + 8 H2O If 36.44 mL of a 0.01652 M KMnO4 solution are required to completely oxidize 25.00 mL of a H2O2 solution, calculate the molarity of the H2O2 solution.
Asked by cheergurliej11 - Tue Feb 12 00:06:38 2008 - - 1 Answers - 0 Comments
A. moles MnO4- = 0.01652 x 0.03644 = 0.0006020 mol have 5/2 = 2.5 x 0.0006020 = 0.001505 mol H2O2 Vol = 36.44ml + 25.00ml = 61.44 ml Molarity = 0.001505 / 0.06144 = 0.02450 mol /L, H2O2
Answered by Michael E - Tue Feb 12 00:15:29 2008
How can I determine the concentration of proteins on calibration curves?
Q. To produce a calibration graph, I have plotted the Absorbance values against the ( known) concentration of a dilution. When I measured a unkown protein, and read the absorbance, I don't know its concentration so I have to read off the concentration in the graph. But how can I do this when I am using excel? I always thought there must be a way to draw a horizontal " line" to the calibration curve and second vertical " line" from the calibration to the concentration values. Problem: I cannot find this function. Can anybody help?
Asked by Marion - Sat Aug 25 15:03:14 2007 - - 1 Answers - 0 Comments
A. assuming your calibration curve is linear - y = a + bx where y is absorbance and x concentration (although log(y) = a + b*log(x) might be better...try it!). Then to get the concentration for an unknown sample you solve for x: x = (y0 - a)/b where y0 is the absorbance for the unknown sample, a is the intercept and b the slope. in Excel, if you have a column of x's and a column of y's you can use the SLOPE function and intercept function to get the slope and intercept. Then use the above equation to get the unknown concentration. I hope this helps.
Answered by Math Chick - Sat Aug 25 20:33:58 2007
Q. To produce a calibration graph, I have plotted the Absorbance values against the ( known) concentration of a dilution. When I measured a unkown protein, and read the absorbance, I don't know its concentration so I have to read off the concentration in the graph. But how can I do this when I am using excel? I always thought there must be a way to draw a horizontal " line" to the calibration curve and second vertical " line" from the calibration to the concentration values. Problem: I cannot find this function. Can anybody help?
Asked by Marion - Sat Aug 25 15:03:14 2007 - - 1 Answers - 0 Comments
A. assuming your calibration curve is linear - y = a + bx where y is absorbance and x concentration (although log(y) = a + b*log(x) might be better...try it!). Then to get the concentration for an unknown sample you solve for x: x = (y0 - a)/b where y0 is the absorbance for the unknown sample, a is the intercept and b the slope. in Excel, if you have a column of x's and a column of y's you can use the SLOPE function and intercept function to get the slope and intercept. Then use the above equation to get the unknown concentration. I hope this helps.
Answered by Math Chick - Sat Aug 25 20:33:58 2007
How to determine initial concentration from molarity and ml?
Q. I am using 4.0 M acetone. If I prepare a solution that is diluted to a total volume of 50.0 mL, using 10 mL of acetone, what is the initial concentration of acetone (in units of M)? There are other factors involved, but I think this is everything needed to answer this question.
Asked by Ella - Wed Oct 7 16:58:54 2009 - - 1 Answers - 1 Comments
A. I suspect you are reading the question incorrectly. If you add solvent to the acetone the solution will become diluted. This would result in a FINAL concentration. The original concentration of the acetone will remain at 4.0 M. However the new, diluted concentration would be (10 ml/ 50 ml) x 4.0 M = 0.80 M is the diluted concentration.
Answered by stush - Wed Oct 7 17:07:24 2009
Q. I am using 4.0 M acetone. If I prepare a solution that is diluted to a total volume of 50.0 mL, using 10 mL of acetone, what is the initial concentration of acetone (in units of M)? There are other factors involved, but I think this is everything needed to answer this question.
Asked by Ella - Wed Oct 7 16:58:54 2009 - - 1 Answers - 1 Comments
A. I suspect you are reading the question incorrectly. If you add solvent to the acetone the solution will become diluted. This would result in a FINAL concentration. The original concentration of the acetone will remain at 4.0 M. However the new, diluted concentration would be (10 ml/ 50 ml) x 4.0 M = 0.80 M is the diluted concentration.
Answered by stush - Wed Oct 7 17:07:24 2009
How can I determine the concentration of a solution from a spectrophotometer?
Q. In this case I have a reading of 640 nanometers @ 1.18 absorbance. This is a solution of 10% m/v CuSO4. How would I be able to calculate the concentration of the solution?
Asked by TheBiochemist - Fri Mar 21 12:01:25 2008 - - 2 Answers - 0 Comments
A. first u have to prepare a calibration curve using standard solution. its as follows: 1. measure the absorbance of standard solution of known concentration for varying concentrations such as 0.5, 1, 1.5 etc. 2. u could maybe do this for 5 solutions (same solution only varying concentration) 3. now plot a graph of absorbance vs. concentration 4. join all the points with a smooth curve 5. draw a line at 1.18 absorbance and drop a perpendicular to get the concentration. all the best - adrian
Answered by Adrian - Fri Mar 21 12:08:14 2008
Q. In this case I have a reading of 640 nanometers @ 1.18 absorbance. This is a solution of 10% m/v CuSO4. How would I be able to calculate the concentration of the solution?
Asked by TheBiochemist - Fri Mar 21 12:01:25 2008 - - 2 Answers - 0 Comments
A. first u have to prepare a calibration curve using standard solution. its as follows: 1. measure the absorbance of standard solution of known concentration for varying concentrations such as 0.5, 1, 1.5 etc. 2. u could maybe do this for 5 solutions (same solution only varying concentration) 3. now plot a graph of absorbance vs. concentration 4. join all the points with a smooth curve 5. draw a line at 1.18 absorbance and drop a perpendicular to get the concentration. all the best - adrian
Answered by Adrian - Fri Mar 21 12:08:14 2008
How do you determine the concentration of ammonia in a window washing solution?
Q. Basically, I need the procedure of how to calculate the concentration of ammonia in Windex.
Asked by Andrea K - Fri Apr 25 00:22:58 2008 - - 4 Answers - 0 Comments
A. can you explain the reason you'd like to know this?
Answered by Chixdiggit - Fri Apr 25 00:32:49 2008
Q. Basically, I need the procedure of how to calculate the concentration of ammonia in Windex.
Asked by Andrea K - Fri Apr 25 00:22:58 2008 - - 4 Answers - 0 Comments
A. can you explain the reason you'd like to know this?
Answered by Chixdiggit - Fri Apr 25 00:32:49 2008
What's the best way to determine residual sugar concentration?
Q. My options are DNS method, GOP method, HPLC and perhaps others as well. However, each of my samples contain either reducing or non-reducing sugars such as glucose, sucrose, etc. May i know which is the best and convenient way to determine the residual sugar concentration for both types of sugar? PS: I posted the same question bout a week ago but i was too preoccupied with my fermentation project and study. The question was then deleted and i haven't had the time to check back. Sorry.
Asked by Zhuge K - Sun Jan 27 05:56:46 2008 - - 1 Answers - 0 Comments
A. Estimation of the optimal concentrations of residual sugar in medium for a fed-batch culture of Baker s yeast has been studied and practiced. The concentrations, however, depended on different species and targets of the biomass, which was expected to be made. Kinetic changes of the residual phosphate salt in the medium conformed to a logarithmic process until the fourth hour during an 11-h culture. The parabolic method (see ref. 9 later in article) might be qualified to maintain the concentrations of residual sugar around 0.15 g/L. It was demonstrated that cell growth followed a sigmoid process during a fed-batch culture, because the cells consumed the nutrient with two metabolic pathways, one was for cell conversion and another was for… [cont.]
Answered by nantinki - Sun Jan 27 10:00:08 2008
Q. My options are DNS method, GOP method, HPLC and perhaps others as well. However, each of my samples contain either reducing or non-reducing sugars such as glucose, sucrose, etc. May i know which is the best and convenient way to determine the residual sugar concentration for both types of sugar? PS: I posted the same question bout a week ago but i was too preoccupied with my fermentation project and study. The question was then deleted and i haven't had the time to check back. Sorry.
Asked by Zhuge K - Sun Jan 27 05:56:46 2008 - - 1 Answers - 0 Comments
A. Estimation of the optimal concentrations of residual sugar in medium for a fed-batch culture of Baker s yeast has been studied and practiced. The concentrations, however, depended on different species and targets of the biomass, which was expected to be made. Kinetic changes of the residual phosphate salt in the medium conformed to a logarithmic process until the fourth hour during an 11-h culture. The parabolic method (see ref. 9 later in article) might be qualified to maintain the concentrations of residual sugar around 0.15 g/L. It was demonstrated that cell growth followed a sigmoid process during a fed-batch culture, because the cells consumed the nutrient with two metabolic pathways, one was for cell conversion and another was for… [cont.]
Answered by nantinki - Sun Jan 27 10:00:08 2008
how to determine the concentration of sodium hydroxide without titrations?
Q. The sodium hydroxide (NaOH) is in aqueous solution and has an approximate concentration on 2 mol/dm3. The experiment must identify the concentration accuratly but must not be a titration!
Asked by hello B - Thu Mar 27 15:58:36 2008 - - 1 Answers - 0 Comments
A. There are several possibilities but the easiest ones are to measure the conductivity of the solution or the pH (which is related to the pOH).
Answered by Sander O - Fri Mar 28 19:39:15 2008
Q. The sodium hydroxide (NaOH) is in aqueous solution and has an approximate concentration on 2 mol/dm3. The experiment must identify the concentration accuratly but must not be a titration!
Asked by hello B - Thu Mar 27 15:58:36 2008 - - 1 Answers - 0 Comments
A. There are several possibilities but the easiest ones are to measure the conductivity of the solution or the pH (which is related to the pOH).
Answered by Sander O - Fri Mar 28 19:39:15 2008
determining the concentration of a solution?
Q. for my lab i have to write a procedure about how i would determine the concentration of a solution then perform that lab. but i have no clue to how you determine the concentration. the only information that i was given is that the solute is calcium chloride in water. also i think for the lab i get 20mL of the solution to use to figure out the concentration. simply, i have to write the procedure but i dont even know where to begin and i can use just about any lab equipment to determine the concentration. any help is greatly appreciated!
Asked by lalalala~ - Thu Nov 22 19:18:52 2007 - - 1 Answers - 0 Comments
A. you can evaporate the water, dehydrate the residue CaCl2 dot 2 H2O, and then weigh the anhydrous CaCl2 @ a molar mass of 110.99 g/mol, (anhydrous), find the moles of CaCl2 Moles / 0.020 litres = molarity --- a person could also find the freezing point of the solution. each "Molal" strength of solute lowers the freezing point of water, (normally ) Celsius), by 1.86 celsius. but there are three moles of ions released from each mole of CaCl2, so take the drop in freezing point and decrease it by a factor of three to get the effect caused by each mole of CaCl2 take that drop due to CaCl2 & divide by 1.86 Celsius/ Molal you end up with a strength for the solution in Molality, which is the moles per kilogram of solvent
Answered by Steve O - Thu Nov 22 23:06:02 2007
Q. for my lab i have to write a procedure about how i would determine the concentration of a solution then perform that lab. but i have no clue to how you determine the concentration. the only information that i was given is that the solute is calcium chloride in water. also i think for the lab i get 20mL of the solution to use to figure out the concentration. simply, i have to write the procedure but i dont even know where to begin and i can use just about any lab equipment to determine the concentration. any help is greatly appreciated!
Asked by lalalala~ - Thu Nov 22 19:18:52 2007 - - 1 Answers - 0 Comments
A. you can evaporate the water, dehydrate the residue CaCl2 dot 2 H2O, and then weigh the anhydrous CaCl2 @ a molar mass of 110.99 g/mol, (anhydrous), find the moles of CaCl2 Moles / 0.020 litres = molarity --- a person could also find the freezing point of the solution. each "Molal" strength of solute lowers the freezing point of water, (normally ) Celsius), by 1.86 celsius. but there are three moles of ions released from each mole of CaCl2, so take the drop in freezing point and decrease it by a factor of three to get the effect caused by each mole of CaCl2 take that drop due to CaCl2 & divide by 1.86 Celsius/ Molal you end up with a strength for the solution in Molality, which is the moles per kilogram of solvent
Answered by Steve O - Thu Nov 22 23:06:02 2007
why is determining the concentration of metal in an ore is by analyzing a small piece of the ore unacceptable?
Q. we've been asked to compare and contrast it with determining the concentration of a solution by analyzing an aliquot of that solution, but my brain can't really come up with a reason !!
Asked by abc - Tue Apr 21 13:35:24 2009 - - 1 Answers - 0 Comments
A. ___Sampling and homogeneity The sample size must be large enough to contain a representative amount of the metal. It is quite possible to take a sample of a heterogeneous ore that has NO metal particle(s). It is also possible to take a sample that is almost nothing but metal. That's why it is nearly impossible to analyze dump piles without grinding up a significant portion of the dump and systematically splitting the total down to a size that can be handled in the lab. And I'll bet you thought the hard part was the analysis! Garbage "in" gives garbage "out"; be sure the garbage "in" is representative.
Answered by SciMann - Wed Apr 22 12:18:21 2009
Q. we've been asked to compare and contrast it with determining the concentration of a solution by analyzing an aliquot of that solution, but my brain can't really come up with a reason !!
Asked by abc - Tue Apr 21 13:35:24 2009 - - 1 Answers - 0 Comments
A. ___Sampling and homogeneity The sample size must be large enough to contain a representative amount of the metal. It is quite possible to take a sample of a heterogeneous ore that has NO metal particle(s). It is also possible to take a sample that is almost nothing but metal. That's why it is nearly impossible to analyze dump piles without grinding up a significant portion of the dump and systematically splitting the total down to a size that can be handled in the lab. And I'll bet you thought the hard part was the analysis! Garbage "in" gives garbage "out"; be sure the garbage "in" is representative.
Answered by SciMann - Wed Apr 22 12:18:21 2009
Determining osmotic concentration and osmotic potential?
Q. I have these information on hand; 1-graph of osmotic potential against molarity of sucrose solution. 2-graph of average change in length of potato strips against molarity of sucrose solution. How should I determine the osmotic concentration and osmotic potential with these information?
Asked by moon ting - Tue Sep 2 10:56:29 2008 - - 1 Answers - 0 Comments
A. For graph 2 if you have plotted % change in length (better to have plotted % change in weight = more accurate) then find the molarity of sucrose at 0% change. This value of sucrose can then be read off from graph 1 to give you the osmotic potential of the potato strips.
Answered by Peter S - Tue Sep 2 11:03:42 2008
Q. I have these information on hand; 1-graph of osmotic potential against molarity of sucrose solution. 2-graph of average change in length of potato strips against molarity of sucrose solution. How should I determine the osmotic concentration and osmotic potential with these information?
Asked by moon ting - Tue Sep 2 10:56:29 2008 - - 1 Answers - 0 Comments
A. For graph 2 if you have plotted % change in length (better to have plotted % change in weight = more accurate) then find the molarity of sucrose at 0% change. This value of sucrose can then be read off from graph 1 to give you the osmotic potential of the potato strips.
Answered by Peter S - Tue Sep 2 11:03:42 2008
From Yahoo Answer Search: 'determined concentration'
Sat Feb 6 14:16:57 2010 [ refresh local cache ]
