Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    2
    ReputationRep:
    3) In this question give all your answers to three significant figures.
    Magnesium nitrate decomposes on heating to form magnesium oxide, nitrogen dioxide
    and oxygen as shown in the following equation.
    2Mg(NO3)2(s) →2MgO(s) + 4NO2(g) + O2(g)

    3 (a) Thermal decomposition of a sample of magnesium nitrate produced
    0.741 g of magnesium oxide.

    3 (a) (i) Calculate the amount, in moles, of MgO in 0.741 g of magnesium oxide.
    -0.0184
    3 (a) (ii) Calculate the total amount, in moles, of gas produced from this sample of magnesium nitrate

    you do 0,.0184 x 5/2?
    why do I multiply by that fraction? I assumed I would multiply is by 2/7, because there's 7 moles of gas in total
    Offline

    3
    ReputationRep:
    (Original post by honeylooloo)
    3) In this question give all your answers to three significant figures.
    Magnesium nitrate decomposes on heating to form magnesium oxide, nitrogen dioxide
    and oxygen as shown in the following equation.
    2Mg(NO3)2(s) →2MgO(s) + 4NO2(g) + O2(g)

    3 (a) Thermal decomposition of a sample of magnesium nitrate produced
    0.741 g of magnesium oxide.

    3 (a) (i) Calculate the amount, in moles, of MgO in 0.741 g of magnesium oxide.
    -0.0184
    3 (a) (ii) Calculate the total amount, in moles, of gas produced from this sample of magnesium nitrate

    you do 0,.0184 x 5/2?
    why do I multiply by that fraction? I assumed I would multiply is by 2/7, because there's 7 moles of gas in total
    There's 7 moles of gas in total correct, but you don't include the moles of MgO. Otherwise you'd be counting the mole ratio of MgO twice. By multiplying by 5/2, you're calculating the moles of the other gaseous products.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by rmndk)
    there's 7 moles of gas in total correct, but you don't include the moles of mgo. Otherwise you'd be counting the mole ratio of mgo twice. By multiplying by 5/2, you're calculating the moles of the other gaseous products.
    thank you
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 24, 2015
Poll
Do you agree with the proposed ban on plastic straws and cotton buds?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.