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# As unit 1 chemistry help jun10 watch

1. 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
2. (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.
3. (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

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