Question

1. Hydrogen sulfide is composed of two elements, hydrogen and sulfur. In an experiment,6.600g hydrogen sulfide is fully decomposed into its elements.

a. if 0.384g og hydrogen is obtained in this experiment, how many grams of sulfur must be obtained?

b. what fundamental law does this experiment demonstrate?

2.only two isotopes of cooper occur naturally 65Cu(atomic mass=62.9296 amu; abundance=69.17%) and 65Cu(atomic mass=64.9278 amu;abundance=30.83%). calculate the average atomic mass cooper.

3. calculate the following quantities

a. mass in grams of 1.223 mol Fe2(SO4)3

b. moles of NH4+ ions in 6.995 g of (NH4)2CO3

c. mass in grams of 7.70 x 10^20 molecules of aspirin , C8H10N4O2

d. molar mass of diazepam if 0.05570 mol has a mass of 15.85 g

4.determine the empirical and molecular formulas

a. ibuprofen contains 75.69% C, 8.80% H, and 15.51% O mass. It has a molar mass of 206 g/mol.

b. Cadaverine contains 58.55% C, 13.81% H, and 27.40% N by mass, and has a molar mass of 102 g/mol.

c. Adrenaline contains 59.0% C, 7.1% H, 26.2% O, and 7.7% and has a molar mass of about 180 g/mol.

5. Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of molecules of water are included in the solid structure. The formula for the Epsom salts can be written as MgSO4 * XH2O where x indicates the number of moles of H2O per mole of MgSO4. When 5.061g of this hydrate is heated to 250 degree c, all of the water hydration is lost, leavng 2.472g of MgSO4. What is the value of x?

Answer 1

2. The average atomic mass of Copper isotopes can be calculated by taking the abundance .

Here the atomic mass= amu and its abundance= and another atomic mass=amu and abundance is

The average atomic mass Cu⁶⁵=

Hence the average mass of Cu is 63.5 amu

1. The balanced chemical reaction

H2S= 6.6 gm which gives 0.384 gm of hydrogen

The amount of Sulphur is = of Sulphur.

This shows law of conservation of mass that means '' the mass is neither created nor destroyed.