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Reacting amounts - using moles

Shorty1992

What mass of nitrogen and hydrogen would be required to make 340g of ammonia?

N2 + 3H2 ----> 2NH3

(the 2 after the N, the 2 after the H and the 3 after the NH are all obviously little numbers to the bottom right of the symbols...)

I know I've got to use moles, but am just a little confused - I've done several other questions like these though, but this one came out at a very small number for the nitrogen part so I think I'm dong this one wrong?

Steps i tried doing was ... find the number of moles of ammonia... find the mole ratio between nitrogen and ammonia and therefore find the mass of nitrogen. So i do know what to do... just can't do it haha must be doing some numbers wrong somewhere

Thankyouuuu if you can help =) xx

Reply 1

Aaron_1507

mass of nitrogen equals 280g mass of hydrogen equals 60g did you get this?

Reply 2

Zygroth

Yeah, you have the correct method.

1 mole of ammonia weighs 17g; in 340g, there are 20 moles of ammonia. 1 mole of nitrogen makes 2 moles of ammonia, so there were 10 moles of nitrogen. Each mole weighs 28g, so 280g of nitrogen were used. Similarly, 3 moles of hydrogen makes 2 moles of ammonia, so 30 moles of hydrogen, with each weighing 2g, makes 60g. Add these together and you have the 340g.