# chem 3A

posted by .

please help me with these homework problems from chemistry because the teacher did not give enough information to some of these chemistry work problems.

1) 50.0 g of aluminum is reacted with excess sulfuric acid. The chemical equation for the reaction is:
2Al + 3H2SO4 --> Al2(SO4)3 + 3H2
If 58.7 L of H2 are collected over water at 20 degree C and 785 torr, what is the mass percent yield?
(Vapor pressure of water at 20 degree C is 17.5 torr.)

2) What is the density of hydrogen, in g/L, under lab conditions? Under STP conditions?

3) Carbon monoxide can be reacted with hydrogen to produce methanol. The chemical equation for the reactions is:
CO(g) + 2H2 --> CH3OH(g)
If 52.10 L of hydrogen gas at STP is completely reacted with excess carbon monoxide gas,what volume in liters of methanol st STP will be produced?

4) The 4.25 grams of sugar (C6H12O6) reacts with sufficient oxygen to produce 3340 mL of carbon dioxide collected over water at 751.9 mm Hg at 24 degree C. Vapor pressure of water at 24 degree C is 22.4 mm Hg. What is the percent yield?

• chem 3A -

I am giving outlines below for solving problems #1 and #2. The others involve the same or similar principles. The general topic is reaction stoichiometry. It is hard to cover such a broad topic adequately through postings here.
Question #1
(a) Use the Ideal Gas Law to find the moles of H2
PV = nRT
P = (785 torr - 17.5 torr)/760 torr/atm = _____ atm
V = given
R = 0.0821 L.atm/K.mol
T = 20.0 + 273 = _____K
*n = (Solve for this variable)
(b) The % yield must be based on the limiting reagent.
Convert 50.0g of Al to moles (divide by 27.0 g/mol)
The mole ratio of H2 to Al is 3/2 = 1.5 according to the chemical equation.
(moles Al)(1.5) = Theoretica l Yield of H2
% yield = [calculated moles H2 / Theoretical yield](100)
Question 2
(a) Density at existing temperature:
Assume you have 1.00 mole of H2 = n
Using the Ideal Gas Law, substitute P = (pressure in atm. you calculated earlier), V = (unknown to solve for), n = 1, R = 0.0821 L.atm/K.mol, T = 293 K. Solve for V (volume in liters). Divide the molar mass of H2 by the calculated volume for 1 mole.
(b) Density at STP:
Divide the molar mass of H2 by 22.4 L.

## Similar Questions

1. ### chemistry

aluminum reacts with sulfuric acid to produce aluminum sulfate and hydrogen gas. how many grams of aluminum sulfate would be formed if 250g H2SO4 reacted with aluminum?
2. ### chemistry

23. aluminum reacts with sulfuric acid to produce aluminum sulfate and hydrogen gas. how many grams of aluminum sulfate would be formed if 250g H2SO4 reacted with aluminum?
3. ### Chemistry- Equation

Aluminum reacts with sulfuric acid to produce aluminum sulfate and hydrogen gas. How many grams of aluminum sulfate would be formed if 250 g H2SO4 completely reacted with aluminum?
4. ### Chemistry

I will do an experiment that includes 4 grams of aluminum hydroxide and iron (III) oxide mixture, where 75% of it is Al(OH)3, and 15 ml of water and 25 ml of 2M KOH will be added and then boiled so that the Al(OH)3 dissolves. It will …
5. ### Chemistry

How many grams of aluminum chloride are produced when 18 g of aluminum are reacted with an excess of hydrochloric acid?
6. ### Chemistry

aluminum reacts with sulfuric acid to produce aluminum sulfate and hydrogen gas. how many grams of aluminum sulfate would be formed if 250 g H2SO4 completly reacted with aluminum
7. ### chemistry

Two solutions were prepared. The first was a 0.672 M solution of aluminum hydroxide and the second was a 0.405 M sulfuric acid solution. 1.) If a total of 500 mL of aluminum hydroxide solution was prepared, how many grams of the solute …
8. ### Chemistry honors

20 grams magnesium metal react with excess oxygen and 28 grams of magnesium oxide are produced in lab what is percent yield?
9. ### Chemistry

Enough concentrated sulfuric acid solution was added to provide 3 grams of sulfuric acid which dissolved i4 grams of pure fluorapatite. How much excess sulfuric acid was used?
10. ### algebra homework help

student missed 11 problems on a Chemistry test and received a grade of 65%. If all the problems were of equal value, how many problems were on the test?

More Similar Questions