More Chem Help Please?

Question

I missed 1 day from being sick so all of this stuff is really throwing me for a loop. I need to understand all of this stuff for an exam tomorrow. Please help if you can and show steps that got you there. Thank you so much in advance!

The Hindenberg was a famous hydrogen-filled dirigible that exploded in 1937. What mass of hydrogen was needed to fill the craft at 23 degrees Celsius and 1.0 atm if the volume was 2.23 x 10^5m^3?

What mass of zinc was needed if the Germans used the reaction of zinc and 10.0-M hydrochloric acid to produce the gas the fill the Hindenberg in the previous problem?

Answer 1

You can find the number of mol of H2 needed using the equation PV = nRT
for this, I used R = 8.206e-5 m³ atm/K mol (that way, no units conversion is needed. If you have a different value for R, you may need to convert your units)
T = 23ºC + 273 = 296K
n = PV/RT
n = [(1.0 atm)(2.23e5 m³)] / [(8.206e-5 m³ atm/K mol)(296K)]
n = 9.18e6 mol H2

for the mass, H2 is 2(1.008) = 2.016 g/mol
9.18e6 mol H2 x 2.016 g/mol = 1.85e7 g H2

second part
Zn + 2HCl --> ZnCl2 + H2
assuming the HCl is in excess...
9.18e6 mol H2 x (1 mol Zn / 1 mol H2) x 65.409 g/mol Zn = 6.00e8 g Zn

Answer 2

For part a, you're going to use the Ideal gas law: PV = nRT

P = 1 atm
T = 23°C = 296K
V = 2.23 x 10^5 m³ = 2.23 x 10^8 liters
R = 0.0820568 Liter-atm/K-mole
n = number of moles of hydrogen

n = PV/RT

Substitute your known values and determine your answer!

Now that you know the number of moles of hydrogen gas (H2) required, it should be easy to figure this out the rest of the way:

Zn (s) + 2 H+ ===> Zn+2 + H2 (g)

You will need LOTS of zinc metal in excess hydrochloric acid, but one mole of zinc metal makes one mole of Hydrogen gas.

From part a, you calculated how many moles of hydrogen gas you needed, so that's how many moles of zinc you need. Using the molecular weight of zinc (65.409 g/mole), it should be easy to calculate the mass of zinc required.

QED!! Good luck on the exam!

Answer 3

Assuming using Ideal Gas Law equation,
pV = nRT
(1.0 x 1.01x10^5) (2.23 x 10^5) = (mass/Mr)(8.31)(23 + 273)
mass/2 = 9.157 x 10^6 mol
mass = 1.83 x 10^7 g or 1.83 x 10^4 kg

2Zn + 2HCl -----> 2ZnCl + H2

mole ratio of Zn:H2 = 2:1
no. of moles of Zn needed = 2 x 9.157 x 10^6 = 1.83 x 10^7
mass of Zn = (1.83 x 10^7) x 65.4 = 1.20 x 10^9 g or 1.20x10^6 kg

Answer 4

There are really people who are very good in chemistry! Sadly, I do not belong to those type of people.