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Mg grams -> (use Mg's molar mass) -> Mg moles -> (use ratio of moles - use balanced equation) -> MgO moles -> (use MgO's molar mass) -> grams MgO

set up the equation:

Mg + O2 --> MgO

(we know the product is MgO and not MgO2 because magnesium has a charge of 2+ while oxygen has a charge or 2-)

balance the equation:

2Mg + O2 --> 2MgO

Molar mass of Mg: 24.31 g/mol

Molar mass of MgO: 44.30 g/mol (add the molar mass of Magnesium - 24.31g/mol and the molar mass of Oxygen - 15.99g/mol together)

(use Periodic Table to find these)

7.0 grams of Mg

To find the moles of Magnesium you use the molar mass of Mg.

(7.0 g Mg)*(1 mol Mg / 24.31 g Mg) =0.2879 moles Mg

notice how the grams cancel to leave you with moles - remember dividing by a fraction is the same as multiplying by the reciprocal

Now use the balanced equation's coefficients and the moles of Mg to determine the number of moles of MgO present.

2Mg + O2 --> 2MgO

2 moles Mg : 2 moles MgO -> divide both sides by 2 and it obviously becomes a 'one to one' ratio. This means that the number of moles of Mg is equal to the number of moles of MgO. This means that there are 0.2879 moles of MgO.

Now that we know MgO's molar mass and the number of moles of MgO we have, the grams of MgO produced can be determined.

(0.2879 moles MgO)*(44.30 g MgO / 1 mol MgO) = 12.75 grams MgO

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14y ago
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11y ago

Let's start by writing a chemical equation for the reaction.

Mg (s) + O2 (g) ----> MgO (s)

According to the Law of Conservation of Mass, the amount of moles of each reagent before the reaction must equal the number of moles of each original reagent after the reaction. We must balance the equation:

2Mg (s) + O2 (g) ----> 2MgO (s)

We assume that the reaction occurs in excess oxygen and that all 8.0 grams of magnesium is completely burned. We then use stoichiometry to find the amount of MgO formed.

(8.0g Mg)(1 mol Mg / 24.3050g Mg)(2 mol MgO / 2 mol Mg)(40.3044g MgO / 1 mol MgO) = 13.3g MgO is formed

So overall 13.3g MgO is formed

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6y ago

You might want to know why 1.99 g is the answer, or how to calculate it. This answer is arrived at as follows:2Mg + O2 ==> 2MgO ... balanced chemical equation

1.2 g Mg x 1 mole/24.3 g = 0.049 moles Mg

Since 2 moles Mg produces 2 moles MgO, this is a 1:1 mole ratio, thus...

0.049 moles Mg will produce 0.049 moles MgO

0.049 moles MgO x 40.3 g/mole = 1.98 grams = 2.0 grams (to 2 significant figures)

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13y ago

Balanced equation.

2Mg + O2 >> 2MgO

8 grams MgO ( 1mol MgO/40.31g )(1 mol O/2 mol MgO )(16g O/1mol O) = 1.59 grams

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13y ago

2Mg + O2 ----->2MgO

48g Mg gives 80 grams of MgO

4g Mg of gives 80/48 x 4= 80/12=20/3= 6.67g of MgO

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6y ago

The magnesium oxide (MgO) obtained theoretically is 1,99 g.

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Q: What is the mass of magnesium oxide when you burn 4 grams of magnesium?
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In the reaction between magnesium and oxygen the mass of magnesium and oxygen was 2.5 grams how much magnesium oxide was formed?

340 grams

Why when magnesium ribbon is burnt the ash is heavier?

When Magnesium burns, it is actually combining with oxygen in the air to form a new compound, magnesium oxide. If we were to carefully weigh a piece of magnesium before and after burning it, you would see that its weight increased by about one third. For example, if you start with 100 grams of magnesium, after the burn you would end up with about 130 grams of magnesium oxide. The fact that the magnesium oxide you create by burning is powdery, means that it takes up more space (size or volume) than the solid magnesium did.

What is the ratio of magnesium oxide mass to the magnesium mass?


Does the coating on a magnesium strip change the mass of magnesium oxide?

The mass of the magnesium will be lower than the mass of the magnesium oxide1 mole of Mg = 24 grams1 mole of MgO = 24 + 16 = 40 grams

Why does magnesium get heavier when its burned?

What happens when magnesium burns? What do you need for magnesium to burn? Will magnesium burn if you have it in a closed container? No. Why not? It needs air. Why does it need air? There is oxygen in the air. Magnesium needs oxygen to burn. So, when magnesium burns, you start with magnesium and end up with a compound that contains both magnesium and oxygen. Magnesium has an atomic weight of 24. Oxygen has an atomic weight of 16. So if you start out with 24 grams of Magnesium you should end up with 40 grams of Magnesium Oxide.

What happens when you magnesium is heated in air?

Magnesium's mass increases as it becomes magnesium oxide.

Why does the mass of magnesium increase when you burn it in air?

It increases because the mass of the magnesium adds to the mass of the oxygen. Also, the magnesium expands and magnesium oxide is formed. The oxidation reaction is: Mg + O2 = 2 MgO

When 24g of magnesium metal is heated in air 40g of magnesium oxide is produced. What mass of magnesium would be needed in order to produce 10g of magnesium oxide?


What happens to the mass when magnesium is heated in air?

When magnesium is heated in air, it forms magnesium oxide and so the total mass increases.

How many grams of oxygen gas is consumed in burning magnesium?

A balanced equation for the reaction is 3 Mg + 3/2 O2 = 3 MgO. the atomic mass of mass of magnesium is about 24.3 and that of oxygen is about 16.0; therefore the mass of magnesium oxide produced is 3 (24.3 + 16.0) = 120.9 grams. (If the specification of "3 moles" of magnesium is considered to have only one significant digit, this answer should be written instead as 1 X 102 grams.)

What is the mass of 24.6 formula units of magnesium oxide?

The mass is 991,5 g.

Magnesium oxide decomposes into magnesium and oxygen If 16.12 of magnesium oxide decomposes to form 9.72 of magnesium what mass of oxygen gas is also released in the reaction?