### chemsitry calculation help!

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• #### Message 1.

Posted by U15228749 (U15228749) on Saturday, 18th May 2013

Hydrochloric acid reacts with magnesium
according to the following equation.

Mg(s) + 2H+ (aq) --> mg2+ (aq) + H2(g)

What ~olume of 4 moll-' hydrochloric acid
reacts with 0.1 m01 of magnesium?
A 25cm3
B 50cm3
C 100cm3
D 200cm3

how would i do this one please

• #### Message 2

, in reply to message 1.

Posted by MissChemTeacher_Bitesize (U15172316) on Tuesday, 21st May 2013

Hydrochloric acid reacts with magnesium according to the following equation.

Mg(s) + 2H+ (aq) --> Mg++ (aq) + H₂(g)

What ~volume of 4 mol l¯ hydrochloric acid reacts with 0.1 moles of magnesium?

A 25cm
B 50cm
C 100cm
D 200cm

The question tells us we have 0.1 moles of magnesium so we can plug that into our mole ratio from our balanced equation.

Balanced Eq: Mg(s) : 2H+
Ratio:………....1……..:….2
From Q:……..0.1 :….…0.2

Using the ratio we know that we now have 0.2 moles of hydrochloric acid (2H+)

Volume of hydrochloric acid = number of moles / concentration
Volume of hydrochloric acid = 0.2 mol / 4.0 mol l¯
Volume of hydrochloric acid = 0.05l or 50cm

Hope you get the hang of this.

Cheers Miss_Chem

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