Q1. What is the molality of a solution containing 3 moles of solute in 500 g of solvent? (2021)
Solution:
Molality (m) = moles of solute / kg of solvent = 3 moles / 0.5 kg = 6 m.
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Q2. What is the formula for calculating the number of moles from mass? (2023)
Solution:
The formula for calculating the number of moles is moles = mass / molar mass.
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Q3. What is the freezing point depression of a solution containing 1 mole of solute in 1 kg of water? (Kf for water = 1.86 °C kg/mol) (2020)
Solution:
Freezing point depression = Kf * m = 1.86 °C kg/mol * 1 mol/kg = 1.86 °C.
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Q4. What is the formula for calculating the number of moles of solute in a solution? (2023)
Solution:
Number of moles = Molarity x Volume (in liters).
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Q5. In a chemical reaction, what does the term 'activation energy' refer to? (2023)
Solution:
Activation energy is the minimum energy required to initiate a chemical reaction.
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Q6. What is the standard temperature and pressure (STP) in Kelvin and atm? (2020)
Solution:
Standard temperature and pressure (STP) is defined as 273 K and 1 atm.
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Q7. If 0.5 moles of NaCl is dissolved in 1 liter of water, what is the molality of the solution? (2022)
Solution:
Molality (m) = moles of solute / kg of solvent. Assuming 1 L of water = 1 kg, molality = 0.5 moles / 1 kg = 0.5 m.
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Q8. If the vapor pressure of pure solvent is 100 mmHg, and the vapor pressure of the solution is 80 mmHg, what is the relative lowering of vapor pressure? (2022)
