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# Chemistry Questions help watch

1. 1. What is the name given to the number of molecules in one mole of CO2?

2. Hydrogen can be made by the reaction of hydrochloric acid with magnesium according to the equation

2HCL + Mg = MgCl2 + H2

What mass of hydrogen is formed when 100cm^3 of hydrochloric acid of concentration 5 mol dm^3 reacts with an excess of magnesium?

I did conc*volume =moles so
5*0.1 = 0.5 moles of hcl in 100cm^3
HCL : Mg 2:1 ratio 0.5/2 = 0.25 moles of Mg excess
then i am stuck (not sure about the next bit)

is it MgCL22 1:1 ratio so there are 0.25 moles in h2
moles*mr = mass so 0.25 * 2= 0.5g
2. dont think that is going to help
3. yes thats right

0.5g of hydrogen gas produced, well done!!

and its avogadros constant for number 1
4. (Original post by coursework.info)
Need more help? You could get help with this question at Coursework.Info
Dear Mr.coursework.info, stop the silly spamming. Or i have to say it. 0wn3d!
5. I don't know what you are worried about ^^ 0.5 grams is right and the number is called Avogadro's Number.
6. Oh good thanks

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Updated: October 27, 2006
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