Question

Hello, can someone help me?

I have a reaction:

2Mg+O2->2MgO

Also, I know that
mass of Mg is 9g
mass of O2 is 8g

What is the mass of MgO?

Answer 1

find the moles f each mg and o2. check which is the limiting reagent. that many moles of mgo will be formed.
also note x moles of mg will give x moles of mgo. but x moles of o2 will give 2x oles of mgo.

Answer 2

1. Find moles of Mg and O2
Mg → 9/24.3 = .37 mol Mg
O2 → 8/16.0 = .50 mol O2

2. Find the limiting reactant (moles of each substance divided by coefficient)
Mg → .37mol ÷ 2 mol = .19
O2 → .50 mol ÷ 1 mol = .5
Limiting reactant (smallest number) = Mg

3. Use moles of Mg to find how many moles of MgO formed
\[\frac{ 2 mol Mg }{ 2 mol MgO } = \frac{ .5 mol O2 }{ x }\]
x = .5 mol MgO formed

4. Convert moles of MgO to grams
MgO → .5(24.3g) + .5(16.0g) = 20.15g

Answer: 20.15 grams MgO