Exercises

Exercise 1. Balance the following chemical equations.

a) Mg + HNO₃ → H₂ + Mg(NO₃)₂

 
b) P₄O₁₀ + H₂O → H₃PO₄

 
c) C₆H₁₄ + O₂ → CO₂ + H₂O

 
d) CaCN₂ + 3 H₂O → CaCO₃ + NH₃

 
e) SiCl₄ + H₂O → SiO₂ + HCl

 
Exercise 2. Ammonia gas and molecular oxygen gas react to produce nitrogen monoxide gas and liquid water.
Write a balanced chemical equation.

 
Exercise 3. Consider the following chemical equation and interpret it in words (Make sure the equation is balanced).
Fe₂O₃ (s) + C (s) → Fe (s) + CO₂ (g)

The balanced equation is: 2 Fe₂O₃ (s) + 3 C (s) → 4 Fe (s) + 3 CO₂ (g)

There are 2 moles of iron(III) oxide that react with 3 moles of solid carbon to produce 4 moles of solid iron and 3 moles of carbon dioxide gas.

Exercise 4. Element A (red spheres) reacts with Element B (blue spheres). Write a balanced chemical equation for this process.

Count the number of reactant molecules and product molecules. The reactant box contains 9 red molecules, A₂ and 3 blue molecules, B₂. The product box contains 6 A₃B molecules.

The reaction is: 9 A₂ + 3 B₂ → 6 A₃B
We can divide the coefficients in the equation by 3 and our balanced equation is:
3 A₂ + B₂ → 2 A₃B

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