Mole Concept

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Q1. How many grams are in 4 moles of potassium chloride (KCl)? (2022)

Solution:

Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Mass = 4 moles x 74.5 g/mol = 298 g.

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Q2. What is the number of moles in 44 grams of carbon dioxide (CO2)? (2023)

Solution:

The molar mass of CO2 is 44 g/mol. Therefore, 44 g of CO2 corresponds to 1 mole.

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Q3. How many molecules are present in 2 moles of water (H2O)? (2022) 2022

Solution:

Number of molecules = moles x Avogadro's number = 2 moles x 6.022 x 10^23 molecules/mole = 1.2044 x 10^24 molecules.

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Q4. What is the mass of 3 moles of NaCl? (2020) 2020

Solution:

Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol. Mass = moles x molar mass = 3 moles x 58.5 g/mol = 174 g.

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Q5. If 1 mole of a gas occupies 22.4 liters at STP, how many liters will 0.5 moles occupy? (2023)

Solution:

At STP, 1 mole of gas occupies 22.4 L. Therefore, 0.5 moles will occupy 0.5 x 22.4 L = 11.2 L.

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Q6. How many grams are in 0.5 moles of glucose (C6H12O6)? (2023)

Solution:

Molar mass of C6H12O6 = 6*12 + 12*1 + 6*16 = 180 g/mol. Mass = 0.5 moles x 180 g/mol = 90 g.

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Q7. How many grams are in 4 moles of sulfuric acid (H2SO4)? (2023)

Solution:

Molar mass of H2SO4 = 2*1 + 32 + 4*16 = 98 g/mol. Mass = 4 moles x 98 g/mol = 392 g.

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Q8. What is the number of moles in 250 mL of a 2 M NaCl solution? (2021)

Solution:

Moles = Molarity x Volume (L) = 2 M x 0.250 L = 0.5 moles.

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Q9. If 0.5 moles of a gas occupy 12.2 liters at STP, what is the molar volume of the gas? (2023)

Solution:

At STP, 1 mole of gas occupies 22.4 liters. Therefore, the molar volume is 22.4 L.

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Q10. What is the volume of 1 mole of an ideal gas at STP? (2019) 2019

Solution:

At STP, 1 mole of an ideal gas occupies 22.4 liters.