Other Chemistry Answers

An unknown fluid, of mass 0.952 is ignited in a 4-liter bomb calorimeter. Both the liquid inside of the calorimeter and the calorimeter itself increased in temperature by 3.914K. Previously, the same calorimeter was calibrated using 1.951 grams of benzoic acid and both the water and the calorimeter increased in temperature by 8.209K. Assume that the density of the water inside the calorimeter is not temperature-dependent. Heat combustion for benzoic acid is 3226kJ per gram.

a. Find the heat of combustion of the fluid.

b. Which compound releases more heat, the unknown fluid or the benzoic acid?

3. If 70 mL of 0.01M HCL is added to 150 mL of 0.1M acetic acid, pH 5.0, what is the resulting pH? Identify the appropriate acid and conjugate base and determine their concentrations in the final solution. 

(A)

A solid sample, containing the element copper, Cu, was quantitatively analysed

by atomic absorption spectroscopy using the following procedure: 0.5250 g of the sample were

dissolved in an appropriate solvent system which was then diluted to 50.0 cm3 5.0 cm3

of this solution were then diluted to 100.0 cm3This 100.0 cm3 of solution was then divided into 5 separate equal volume aliquots with each aliquot being placed in separate 50.0 cm3volumetric flasks. Various volumes of a standard stock solution of Cu (concentration = 250 ppm) were then added to these flasks and all the flasks were then diluted to volume after the additions. The resulting solutions were then analysed for Cu using an atomic

absorption spectrophotometer.

The following measurements were obtained:

Atomic Absorbance Volume of 250 ppm Cu added to flasks (cm3)

0.22 0.0

0.42 0.4

0.63 0.8

0.84 1.2

1.04 1.6

Use the data to calculate the % Cu in the original solid sample. (12 marks)