Question

28. Combustion needs oxygen, but it doesn't have to come

from 02. Magnesium can burn in pure carbon dioxide
once the reaction is started.
a. Write and balance a displacement reaction for
magnesium buring in carbon dioxide (CO2)
b. 10.0 grams of magnesium is burned in excess
carbon dioxide. How much carbon is produced?
c. How much carbon dioxide is consumed to burn the
10.0 g of magnesium?
d. What is the minimum volume of carbon dioxide gas
at STP required to completely burn 10.0 g of Mg.

Answer 1

Step-by-step explanation:

a) Chemical equation:

2Mg + CO₂ → 2MgO + C

b)

Mass of magnesium = 10.0 g

Mass of carbon produced = ?

Solution:

Number of moles of magnesium = mass/ molar mass

Number of moles = 10.0 g/ 24 g/mol

Number of moles = 0.42 mol

Now we will compare the moles of magnesium and carbon.

Mg : C

2 : 1

0.42 : 1/2×0.42 = 0.21 mol

Mass of carbon:

Mass = number of moles × molar mass

Mass = 0.21 mol × 12 g/mol

Mass = 2.52 g

C)

Number of moles of magnesium = mass/ molar mass

Number of moles = 10.0 g/ 24 g/mol

Number of moles = 0.42 mol

Now we will compare the moles of magnesium and carbon dioxide.

Mg : CO₂

2 : 1

0.42 : 1/2×0.42 = 0.21 mol

Mass of carbon dioxide:

Mass = number of moles × molar mass

Mass = 0.21 mol × 44 g/mol

Mass = 9.24 g

d)

Volume of carbon dioxide:

PV = nRT

V = nRT/P

V = 0.21 mol ×0.0821 atm. L / mol.k × 273 k / 1 atm

V = 4.71 L