Chemical Equations and Reactivity

Questions and Answers

What is the molar volume of an ideal gas?

22.7 dm3 mol–1

What steps are involved in writing a chemical equation?

Write down the word equation. 2. Convert to chemical formulas. 3. Balance the equation. 4. Add state symbols.

How do you convert mass into moles?

Using the formula n = m/M.

What determines the yield of a chemical reaction?

The limiting reactant Signup and view all the answers

What is a limiting reactant?

A substance which is completely consumed in a chemical reaction. Signup and view all the answers

What is an excess reactant?

A reactant which remains after the reaction has taken place. Signup and view all the answers

The formula to find moles is n = ______

m/M Signup and view all the answers

What is the mole ratio of Fe2O3(s) to CO(g) in the reaction?

1:3 Signup and view all the answers

How is the volume of a gas calculated from moles?

Using the formula V = n x Vm Signup and view all the answers

To find the volume of carbon monoxide, the total moles needed is ______

601.2 mol Signup and view all the answers

Study Notes

Chemical Equations

Begin with a word equation, placing reactants on the left and products on the right of the reaction arrow.
Convert reactants and products into their respective chemical formulas.
Balance the chemical equation to ensure the number of atoms of each element is conserved.
Include state symbols (s, l, g, aq) to indicate the physical state of each substance.

Reacting Ratios and Moles

Coefficients in balanced equations represent moles, which measure the amount of substance.
Molar volume of an ideal gas is 22.7 dm³ mol⁻¹, essential for calculations involving gases.

Calculating Mass, Concentration, or Volume

Mole ratios from balanced equations help convert known values (mass, concentration, volume) into moles of unknowns.
To find mass of a compound, such as sodium oxide (Na₂O):
- Use the periodic table to find molar mass.
- Apply the formula for mass (n = \frac{m}{M}) (n = moles, m = mass, M = molar mass).

Problem-Solving Steps

Balance the chemical equation and identify known and unknown reactants/products.
Convert the known quantity to moles.
Apply the mole ratio from the balanced equation to find moles of the unknown substance.
Convert moles of the unknown back to desired units.

Aqueous Solution Calculations

For aqueous solutions, use the formula (n = CV) where C is concentration and V is volume.

Worked Example

For the reaction between 32.00 kg of iron(III) oxide (Fe₂O₃) and carbon monoxide (CO):
- Balance the equation: Fe₂O₃(s) + 3CO(g) → 2Fe(s) + 3CO₂(g).
- Convert 32 kg of Fe₂O₃ to grams (32000 g).
- Calculate moles of Fe₂O₃ using (n = \frac{m}{M}): (n = \frac{32000}{159.7} \approx 200.4 mol).
- Determine the mole ratio with CO (1:3), leading to (200.4 mol) of Fe₂O₃ requiring (601.2 mol) of CO.
- Calculate the volume of CO using (V = n \times Vm): (V = 601.2 \times 22.7 \approx 13647 dm³ (1.365 \times 10^4 dm³)).

Limiting and Excess Reactants

Limiting reactant: the substance completely consumed during the reaction, determining the maximum yield of product.
Excess reactant: the substance that remains after the reaction has completed.
To identify the limiting reactant:
- Calculate the number of moles of each reactant.
- Compare moles available with the stoichiometric ratios from the balanced equation.
To find the excess reactant:
- Convert both reactants to moles.
- Identify how much of each is consumed and the remainder left.

Description

This quiz covers the fundamentals of writing and balancing chemical equations, focusing on reactivity. You will learn how to convert word equations into chemical formulas and the importance of coefficients in balanced equations. Test your understanding and ability to apply these concepts effectively.