Question

Hydrogen gas is produced when we react magnesium metal with hydrochloric acid:

Mg + 2HCl = MgCl2 + H2O

a) If 4.50g of hydrogen gas is collected at STP, what volume of hydrogen does this represent?

b) If 0.52 mol of magnesium completely reacted, what amount of hydrogen is (in moles) would be produced at STP? How many grams of hydrogen si this?

Answer 1

i've already done the first part and it goes like this.....

Given: \[m_H2= 4.50g, STP conditions, M_H2= 2.02g/mol\]
\[required: Volume of H_2\]
\[Solution: V_1/N_1 = V_2/N_2\]

4.50g/1mol/2.02g.....grams cancels out and i get 2.227mol

2.227mol X 22.4L/1mol, where mols cancels out and i get 49.72L

Answer 2

for the second question i get a weird number.

Answer 3

Since there is a 1:1 ratio of Mg to H2. there would be .52 moles of H2 gas. Take that value and multiply it by the molar mass of H2, 2.016g/mol and you will get 1.05 g.

Answer 4

never mind i was gettign the same answer but i just rechecked it and i was lookign at the wrong answer -_-

Answer 5

\[Mg + 2HCl \rightarrow MgCl _{2}+ H _{2}\]
This should be the equation.

Answer 6

yah i know i made a mistake while typing too fast.

Answer 7

No prob. Good luck.

Answer 8

again thanks alot!!!!!

Answer 9

the first time i looked at the back of the book, i saw like 61.4g LOL