what mass of oxygen reacts with 192g of Magnesium?
I'm not sure whether to divide the mass by Magnesium or oxygen to find the number of moles???
Find the moles of Magnesium= mass/ AR= 192/24
Whatever the answer to this is, divide it by 2 to find the moles of oxygen because the ratio of Mg to 02 is 2:1
To find the mass of 02= moles x Mr
isn't is 192/48 because it#s 2Mg
could someone just take me through each step please
2Mg +02= 2MgO
2. You need to find the moles of magnesium:
(We account for the ratio of 2Mg: 02 later on)
3. You use your answer to 2. to find the moles of oxygen:
The ration of 2Mg:02 is 2:1 so you divide the previous answer by 2 to get the moles of oxygen
4. You use your answer to 3. to find the mass of oxygen:
Mass= Moles x Mr
Mass= (answer to 3) x 32 (02 is a diatomic molecule so it's 16 x 2)
Is that any clearer?
It is the ratio at which things react.
When Mg reacts with 02, you need 2 Mg as the equation is:
2Mg + 02 ----> 2Mg0.
Therefore the moles of 02 is half that of 2Mg.
I would divide the 192 (mass)/ 24 (Mr) and then divide by two (2 Mgs to one oxygen) and times by 32 (02) to get the answer.
Here is my advice for any style of question regarding reacting masses
x (mass in g)/ y of either product/reactant and then multiply by the other.