Constant-volume calorimeters are sometimes calibrated by running a combustion reaction of known ΔE and measuring the change in temperature. For example, the combustion energy of glucose is 15.57 kJ/g. When a 2.000 g sample of glucose burns in a constant volume calorimeter, the calorimeter temperature increases from 21.45 to 23.34°C. Find the total heat capacity of the calorimeter (in kJ/K).

Consider a crystallization of sulfanilamide in which 10ml of hot 95% ethyl alcohol is added to 0.10g of impure sulfanilamide. After the solid has dissolved, the solution is cooled to room temperature and then placed in an ice water bath. No crystals form, even after scratching with a glass rod. explain why this crystallization failed. What would you have to do at this point to make the crystallization work??

explain how PLA is biodegradable?

Draw several ammonia molecules in Lewis structure, then add in some hydrogen bonds where appropriate; label the atoms that are involved in the hydrogen bonds as partially positive or negative.

how is PLA synthesized

Which of these is NOT a true statement? (Why is the answer B?)

a. All Lewis bases are also Brønsted-Lowry bases.

b. All Lewis acids contain hydrogen.

c. All Brønsted-Lowry acids contain hydrogen.

e. All Lewis acids are electron deficient.

f. According to the Brønsted-Lowry theory, water is both an acid and a base.

A sample of solid Ca(OH)2 was stirred in water at a certain temperature until the solution contained as much dissolved Ca(OH)2 as it could hold. A 77.3-mL sample of this solution was withdrawn and titrated with 0.0573 M HBr. It required 80.4 mL of the acid solution for neutralization.

(a) What was the molarity of the Ca(OH)2 solution?

(b) What is the solubility of Ca(OH)2 in water, at the experimental temperature, in grams of Ca(OH)2 per 100 mL of solution?

Lab was done on bromination of acetanilide, aniline, anisole.

One of three compound was dissolved in glacial acetic acid. Bromine/hydrobromic acid mixture was added and continue to stir for 20minutes (for anisole heat the reaciton at 80C for 40minutes)

afther 20 minutes, trasnfer the mixture to a flask containing water and satuarted sodium bisulife solution. Place it in ice bath and let it crystalize. Do recrystalizaiton.

1. If the yield was low, explain the reason for the low yield (NOT including human error)

2. When identification of the product based on melting point and NMR differs, why they might differ and which technique you have more confidence in.

Use molecular orbital theory to explain why the bond energy of an O₂ molecule is less than that of a O₂⁺ ion.

Learning Group Problem Chp 9, problem 1.

1. Given the following information, elucidate the structures of compounds A and B. Both compounds are soluble in dilute aqueous HCl, and both have the same molecular formula. The mass spectra of A and B have M+ 149. Other spectroscopic data for A and B are given below. Justify the structures you propose by assigning specific aspects of the data to the structures. Make sketches of the NMR spectra.

(a) The IR spectrum for compound A show two bands in the 3300-3500 cm-1 region. the broadband protons decoupled 13C NMR spectrum displayed for the following signals:
A: 13C NMR: 140 (C), 127 (C), 125 (CH), 118 (CH), 24 (CH2), 13 (CH3)

(b) The IR spectrum for compound A show no bands in the 3300-3500 cm-1 region. the broadband protons decoupled 13C NMR spectrum displayed for the following signals:
B: 13C NMR: 147 (C), 129 (CH), 115 (CH), 111 (CH), 44 (CH2), 13 (CH3)

1.00 mL of a 2.95 X10^-4 M solution of oleic acid is diluted wth 9.00 mL of petroleum ether, forming solution A. Then 2.00 mL of solution A is diluted with 8.00 mL of petroleum ether, forming solution B. How many grams of oleic acid are 5.00 mL of solution B? (Molar mass for oleic acid=282g/mo)

A. What was the ?H value obtained for NH3 + HCl

A sample of gas weighs 4.406g and has a volume of 1100.00 mL at 665.0 torr and 37.0 degrees C. What is the molar mass? Please show work.

Rewrite the procedure in third person & in past tense:

Procedure

You will be provided with post-mitochondrial supernatant fractions from rat liver of control rats and phenobarbitone-treated rats. Carry out the assay for drug metabolism as follows.

A

1. Take 4 ml incubation medium (containing substrate aminopyrine) into each test flask.
2. Take 4 ml incubation medium (containing no substrate into one flask (reagent blank)).
3. Add 700 ml 0.25 M sucrose solution to all flasks.
4. Pre-incubate all flasks at 37 °C for five minutes.

B

1. Add 300 ml liver homogenate supernatant to all flasks.
2. Shake unstoppered at 37 °C for 30 minutes.

C

1. Add 2 ml ZnSO₄.7H₂O (8.9%) solution to all flasks. Mix.
2. Remove flask from bath and leave for five minutes.
3. Add 2 ml saturated Ba(OH), 8H₂O solution. Mix well.
4. Transfer to 10 ml test tube and centrifuge at 200rpm for 10 minutes.

D

1. Prepare formaldehyde standards. Pipette 2.5 ml portions of each concentration into a test tube (LPS).  Use 2.5 ml water as a blank.
2. Add 1.5.ml Nash reagent to each tube and vortex.

E

1. Place 2.5 ml supernatant (from tubes treated under section C) into test tube.
2. Add 1.5 .ml Nash reagent. Vortex
3. Incubate all tubes (including standards) at 60 °C for 30 minutes.
4. Leave to cool.  Read absorbency at 412 nm against a blank reagent.
5. Read formaldehyde standards against a reagent blank.
6. Express results as ~mmol formaldehyde formed/h/g/liver (homogenate).