Question

When magnesium chloride reacts with water, 5.85 L HCl(g) is produced.

molar mass of HCl = 36.5 g/mol
molar mass of MgCl2 = 95.2 g/mol

How many moles of HCl was produced?

How many moles of MgCl2 reacted?

What mass of MgCl2 reacted?

Answer 1

Hmm, strange product formation, but I am assuming they are saying this is taking place: \(\sf \color{blue}{MgCl_2 + 2~H_2O \rightarrow Mg(OH)_2 + 2~HCl}\)

ALWAYS, start by writing down your balanced chemical equation for these types of problems. And \(\sf \color{red}{write~down~what~you're~given}\) to start with.

In this problem, you have: \(\sf 5.85~L\) of hydrochloride gas. Assume the reaction is done at STP, meaning standard temperature and pressure, (this means this reaction was done at room temperature ~20-25 degree celsius and 1 atm pressure). So, use 22.4 Liters per mole. This will allow you to get moles of hydrochlorous acid.

5.85 \(\sf \cancel{L} \times \frac{mole}{22.4~\cancel{L}}\) = _______ mol of hydrochloric acid (HCl).

Next, refer to your balanced chemical equation that I wrote up above. MAKE SURE IT IS BALANCED! I did it fairly quickly, but for reassurance, DOUBLE CHECK IT YOURSELF!

You're process is the same as the one above. Use dimensional analysis to cancel units to obtain what you want.

Answer 2

Keep in mind that you have a 2:1 ratio when converting from HCl \(\rightarrow\) MgCl\(_2\)