A0.200 g sample of magnesium and zinc is placed in a rigid 1 l vessel containing dry air at 25 °c and 1 atm. the magnesium and zinc are treated with dilute sulfuric acid to produce hydrogen gas according to the following balanced reactions: mg (s) + h2so4 (aq) → mg2+ (aq) + so42– (aq) + h2 (g) zn (s) + h2so4 (aq) → zn2+ (aq) + so42– (aq) + h2 (g) the hydrogen gas is then completely combusted in the same vessel to form water as a product. the vessel is then cooled back to 25 °c (assume that all the water condenses) and the pressure is found to be 0.95 atm. what is the mass percentage of magnesium in the mixture?

Explanation:

Hello,

In this case, one first must consider the final pressure in order to compute the consumed hydrogen mass converted into water as shown below, considering the ideal gas equation for the gaseous water:

Next, taking into account the hydrogen combustion process:

One computes the consumed hydrogen mass during as follows:

Now, such mass equals the yielded hydrogen during sample's treatment with dilute sulfuric acid:

Thereby, by means of both reactions, the hydrogen mass equals:

Whereas accounts for the hydrogen yielded by the magnesium and by the zinc which are computed in terms of the stoichiometry and the initial sample's composition as shown below:

Now, as the addition between the percentages equals one, the mass of hydrogen due to zinc could be rewritten as:

In such a way, one obtains:

Best regards.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o