Expository essay quiz Grade 11

📚 Quick Study Guide

• ⚛️ Atomic Mass: The weighted average mass of all isotopes of an element, found on the periodic table. Measured in atomic mass units (amu).
• ➕ Molar Mass: The mass of one mole of a substance, numerically equal to the atomic or molecular weight in grams. Example: The molar mass of water ($H_2O$) is approximately 18.01 g/mol.
• ⚖️ Stoichiometry: The calculation of quantitative (measurable) relationships of the reactants and products in a balanced chemical equation.
• ➗ Mole Concept: 1 mole = $6.022 \times 10^{23}$ particles (Avogadro's number). Use this to convert between moles and number of atoms/molecules.
• 🌡️ Standard Temperature and Pressure (STP): 0°C (273.15 K) and 1 atm. At STP, 1 mole of any gas occupies 22.4 L.
• 📝 Empirical Formula: The simplest whole number ratio of atoms in a compound.
• 🧪 Molecular Formula: The actual number of atoms of each element in a molecule. It is a multiple of the empirical formula.

🧪 Practice Quiz

1. Which of the following is the correct definition of molar mass?
   1. A) The mass of one atom of an element.
   2. B) The mass of one mole of a substance.
   3. C) The number of atoms in one gram of a substance.
2. What is the molar mass of $NaCl$ (Sodium Chloride)? (Na = 22.99 g/mol, Cl = 35.45 g/mol)
   1. A) 58.44 g/mol
   2. B) 12.46 g/mol
   3. C) 75.22 g/mol
3. What does STP stand for in chemistry?
   1. A) Standard Temperature and Pressure
   2. B) Standard Time Period
   3. C) Stable Temperature Point
4. How many molecules are there in 2 moles of $H_2O$?
   1. A) $3.011 \times 10^{23}$
   2. B) $1.2044 \times 10^{24}$
   3. C) $6.022 \times 10^{23}$
5. What is the empirical formula of a compound with the molecular formula $C_6H_{12}O_6$?
   1. A) $C_3H_6O_3$
   2. B) $CH_2O$
   3. C) $C_2H_4O_2$
6. Which of the following is used to convert grams to moles?
   1. A) Density
   2. B) Molar Mass
   3. C) Volume
7. In a balanced chemical equation, the coefficients represent:
   1. A) The mass of the reactants and products.
   2. B) The number of moles of reactants and products.
   3. C) The density of the reactants and products.