CHEM
Which bond is longer: a single bond or a triple bond?
Answer: Single bond
Name the acid: HNO₃
Answer: Nitric acid
Identify the reaction type:
2KClO₃ → 2KCl + 3O₂
Answer: Decomposition
What is the molar mass of Ca(OH)₂?
Answer: 40.08 + (2 × 16.00) + (2 × 1.01) = 74.10 g/mol
If 88 g of CO₂ are produced, how many mol is that?
Answer: 88 / 44.01 = 2 mol
Which bond is stronger: a single bond or a triple bond?
Answer: Triple bond
Write the formula for: hydrofluoric acid
Answer: HF
Hydrochloric acid reacts with sodium hydroxide to form water and sodium chloride.
Write the balanced chemical equation.
Answer: HCl + NaOH → H₂O + NaCl
Find the percent composition of carbon in CH₄.
Answer:
Carbon mass = 12.01 g
Molar mass of CH₄ = 16.05 g
% C = (12.01 / 16.05) × 100 = 74.8%
Given:
N₂ + 3H₂ → 2NH₃
If you have 5 mol N₂ and 6 mol H₂, what is the limiting reactant?
Answer: H₂ (needs 15 mol, only have 6)
3. Draw the Lewis structure for H₂O and name its shape.
Answer:
Lewis structure:
mathematicaCopyEdit
Shape: Bent
What is the shape of BF₃?
Answer: Trigonal planar
dentify the reaction type:
Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃
Answer: Double displacement
Find the empirical formula of a compound with 40% C, 6.7% H, and 53.3% O.
Answer: CH₂O
If the theoretical yield is 10 g and actual yield is 7 g, what is the percent yield?
Answer: (7 / 10) × 100 = 70%
Name this compound: PCl₅
Answer: Phosphorus pentachloride
Balance the following equation:
Al + O₂ → Al₂O₃
Answer: 4Al + 3O₂ → 2Al₂O₃
What is Avogadro’s number?
Answer: 6.022 × 10²³
If 2 mol H₂ react with O₂, how many mol of H₂O are formed?
Answer: 2 mol H₂O
25. A gas at 2.0 atm is compressed from 4.0 L to 2.0 L at constant temperature. What is the new pressure?
(Boyle’s Law: P₁V₁ = P₂V₂)
Answer:
2.0 atm × 4.0 L = P₂ × 2.0 L → P₂ = 4.0 atm
Write the formula for: carbon dioxide
Answer: CO₂
Identify the reaction type:
2H₂ + O₂ → 2H₂O
Answer: Synthesis
How many molecules are in 2.5 mol of CO₂?
Answer: 2.5 × 6.022 × 10²³ = 1.51 × 10²⁴ molecules
How many grams of CO₂ are produced from 1 mol of C?
Answer: 44.01 g (CO₂ molar mass)
If 80 g of H₂O are produced but 90 g were expected, what is the percent yield?
Answer: (80/90) × 100 = 88.9%