when you were performing freezing point experment the cyclohexane was contaminate before it was placed in...
Homework Answers
Solution:
The contamination in cyclohexane causes lowering of freezing point. It also broaden the range of melting points. The contamination of cyclohexane disrupted the crystal lattice energy hence causes a lowering of melting point or freezing point. Therefore, contamination causes the lowering of vapor pressure. Thus, the observed vapor pressure is less.
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when you were performing freezing point experment the cyclohexane
was contaminate before it was placed in...
When 12.6-grams of an unknown compound is placed in 0.116-kg of benzene, the freezing point is...
When 12.6-grams of an unknown compound is placed in 0.116-kg of benzene, the freezing point is changed by 2.34°C. The value of Kf= 4.90°C/m for benzene. Determine the molar mass of the unknown compound. Answer to 1 decimal place and include your units. Answer: Determine the molality of a solution when 32.3 grams of ethanol, C2H5OH (Molar mass = 46.08 g/mol) is dissolved in 0.947 kg of water. Answer to 2 decimal places. Answer: Find the freezing point of a...
1. A student performed a freezing point determination and calculated the molar mass of an unknown...
1. A student performed a freezing point determination and calculated the molar mass of an unknown like you did in this experiment. The only difference in procedure was that when determining the freezing point of the unknown-naphthalene mixture, they started with a clean empty test tube. If the following errors occurred, how would each affect the calculated molar mass of the solute (too high, too low, or no change)? Explain your answers. a. The thermometer used actually read 2.0 celcius...
When performing an experiment, you miss-calibrated your pH meter and all of the readings were 0.25...
When performing an experiment, you miss-calibrated your pH meter and all of the readings were 0.25 units higher than actual. How would this affect your calculated values for Ka? Provide a calculation to support your claim.
Molecular Mass by Freezing point Depression (Preliminary Lab) The following errors occurred when the above experiment was carried out
Molecular Mass by Freezing point Depression (Preliminary Lab) The following errors occurred when the above experiment was carried out. How would each affect the calculated molecular mass of the solute (too high,too low, no effect)? Explain your answer. (a) The thermometer uses actually read 1.4C too high. (b) Some of the solvent was spilled before the solute was added.
Chemistry: Molar mass determination and freezing point depression. If your unknown solute sample weighed 0.634 grams,...
Chemistry:
Molar mass determination and freezing point depression.
If your unknown solute sample weighed 0.634 grams, but some of it stuck to the test tube wall when you were pouring it in and did not dissolve in the t-butyl alcohol, what sort of error will this cause in the calculated molar mass of your unknown solute? Explain. What would be the freezing point of an aqueous solution that contains 10.3 grams of ethylene glycol [(C_2H_4(OH)_2] in 100 mL of water?
Date Name Lab Section Partner(s) Determination of Molar Mass by Freezing Point Depression Data: Mass of...
Date Name Lab Section Partner(s) Determination of Molar Mass by Freezing Point Depression Data: Mass of empty test tube 2.2.6! Mass of test tube plus approximately 10.0 g of benzophenone 33.39 The difference is the mass of benzophenone (solvent) 8 kg Mass of unknown (-1.0 g) 1:09: 48.50°c 42.08. Freezing point of pure benzophenone Freezing point of benzophenone containing the unknown The difference is A fp CO Calculations: (Show set-up with cancellation of units) 1. molality of solution 2. moles...
Freezing Point Depression: Determination of the Molar Mass of an Unknown Substance Laboratory Record Unknown Identifier...
Freezing Point Depression: Determination of the Molar Mass of an Unknown Substance Laboratory Record Unknown Identifier #4 (All unknowns are nonelectrolytes, soi-1) Determination of the freezing point of pure l-butyl alcohol: (Record time-temperature data on the next page) 29.62 1. Mass of empty test tube 2. Mass of test tube and t-butyl alcohol after determination of freezing point of pure t-butyl alcohol 50.25 20.71 3. Mass of t-butyl alcohol Determination of the molar mass of an unknown: (Record time-temperature data...
When performing a melting point on a solid compound, 2 melting point determinations were made. One...
When performing a melting point on a solid compound, 2 melting point determinations were made. One sample, which was 1 mm in height in the capillary, possessed a melting point of 150-151°C. The other sample was 25 mm in height. What would you expect the approximate melting point to be for this 25 mm sample, if the heating rate for both samples was 2 degrees per minute? (Hint: use algebra to solve the mp range) 4.
how would the calculated molar mass change if the following experimental problems were encountered? Explain the...
how would the calculated molar mass change if the following experimental problems were encountered? Explain the reasons for your answer. a. the unknown was impure and only part of the unknown dissolved in the Lauric acid. b. your unknown contained a substance that produced two ions per molecule of unknown when dissolved in the Lauric acid. (experiment on Lauric acid for freezing point depression)
If you can please explain step by step for each question. Problem 1, Question 1. Cyclohexae,...
If you can please explain step by step for each question.
Problem 1, Question 1.
Cyclohexae, C6H12, melts at 6.55 oC and has a freezing point
depression constant of kfp = -20.0 oC/m (where m
is molality). You want to determine the molar mass of an unknown
pure compound using the colligative property of freezing point
depression. You weigh out 83.561 g of cyclohexane, and confirm that
its melting point is 6.55 oC. You then mix 2.566 g of your...
When 12.6-grams of an unknown compound is placed in 0.116-kg of benzene, the freezing point is changed by 2.34°C. The value of Kf= 4.90°C/m for benzene. Determine the molar mass of the unknown compound. Answer to 1 decimal place and include your units. Answer: Determine the molality of a solution when 32.3 grams of ethanol, C2H5OH (Molar mass = 46.08 g/mol) is dissolved in 0.947 kg of water. Answer to 2 decimal places. Answer: Find the freezing point of a...
Chemistry:
Molar mass determination and freezing point depression.
If your unknown solute sample weighed 0.634 grams, but some of it stuck to the test tube wall when you were pouring it in and did not dissolve in the t-butyl alcohol, what sort of error will this cause in the calculated molar mass of your unknown solute? Explain. What would be the freezing point of an aqueous solution that contains 10.3 grams of ethylene glycol [(C_2H_4(OH)_2] in 100 mL of water?
Date Name Lab Section Partner(s) Determination of Molar Mass by Freezing Point Depression Data: Mass of empty test tube 2.2.6! Mass of test tube plus approximately 10.0 g of benzophenone 33.39 The difference is the mass of benzophenone (solvent) 8 kg Mass of unknown (-1.0 g) 1:09: 48.50°c 42.08. Freezing point of pure benzophenone Freezing point of benzophenone containing the unknown The difference is A fp CO Calculations: (Show set-up with cancellation of units) 1. molality of solution 2. moles...
Freezing Point Depression: Determination of the Molar Mass of an Unknown Substance Laboratory Record Unknown Identifier #4 (All unknowns are nonelectrolytes, soi-1) Determination of the freezing point of pure l-butyl alcohol: (Record time-temperature data on the next page) 29.62 1. Mass of empty test tube 2. Mass of test tube and t-butyl alcohol after determination of freezing point of pure t-butyl alcohol 50.25 20.71 3. Mass of t-butyl alcohol Determination of the molar mass of an unknown: (Record time-temperature data...
When performing a melting point on a solid compound, 2 melting point determinations were made. One sample, which was 1 mm in height in the capillary, possessed a melting point of 150-151°C. The other sample was 25 mm in height. What would you expect the approximate melting point to be for this 25 mm sample, if the heating rate for both samples was 2 degrees per minute? (Hint: use algebra to solve the mp range) 4.
If you can please explain step by step for each question.
Problem 1, Question 1.
Cyclohexae, C6H12, melts at 6.55 oC and has a freezing point
depression constant of kfp = -20.0 oC/m (where m
is molality). You want to determine the molar mass of an unknown
pure compound using the colligative property of freezing point
depression. You weigh out 83.561 g of cyclohexane, and confirm that
its melting point is 6.55 oC. You then mix 2.566 g of your...
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