Stoichiometry Test

1. What is stoichiometry? A) The study of chemical reactions that occur in living organisms B) The study of quantitative relationships between reactants and products in a chemical reaction C) The study of chemical equilibrium D) The study of reaction rates

2. What is a limiting reactant in a chemical reaction? A) The reactant that controls the amount of product formed B) The reactant that speeds up the reaction C) The reactant that is present in the smallest amount D) The reactant that reacts most slowly

3. What is an excess reactant? A) A reactant that causes the reaction to go faster B) A reactant that is used up first C) A reactant that is left over after the reaction is complete D) A reactant that causes the production of byproducts

4. The coefficients in a balanced chemical equation indicate: A) The number of molecules only B) The number of moles only C) Both the number of molecules and the number of moles D) The mass in grams of each substance

5. Which of the following is true about the law of conservation of mass? A) The total mass of products always exceeds the total mass of reactants B) The total mass of reactants equals the total mass of products C) The total mass of reactants always exceeds the total mass of products D) Mass is not conserved in chemical reactions

6. What determines the amount of product that can form in a reaction? A) The amount of catalyst present B) The molar mass of the reactants C) The limiting reactant D) The temperature of the reaction

7. In the stoichiometric equation for the Haber process (N₂ + 3H₂ → 2NH₃), if 2 moles of ammonia are produced, how many moles of hydrogen were consumed? A) 2 moles B) 3 moles C) 6 moles D) 1 mole

8. When mass has been conserved in a chemical reaction: A) The number of molecules of reactants equals the number of molecules of products B) The mass of reactants equals the mass of products C) The volume of reactants equals the volume of products D) The number of atoms of each element can be variable 

Solutions are defined as: A) Heterogeneous mixtures of two or more substances B) Homogeneous mixtures of two or more pure substances C) Pure substances with uniform properties D) Mixtures that separate into visible layers

1. In a solution, the substance being dissolved is called the: A) Solvent B) Precipitate C) Solute D) Mixture
   
   

2. The process in which solvent particles pull solute particles apart and surround them is called: A) Precipitation B) Crystallization C) Solvation D) Dissolution
   
   

3. Which of the following best explains why ionic compounds dissolve in water? A) Dispersion forces between water and ionic compounds B) Ion-dipole interactions that overcome the lattice energy C) Covalent bonds forming between water and ionic compounds D) Hydrogen bonding between water molecules
   
   

4. The principle "like dissolves like" means: A) Only identical substances can dissolve in each other B) Substances with similar intermolecular forces tend to dissolve in each other C) Polar substances always dissolve better than nonpolar substances D) Only compounds with the same chemical formula can dissolve each other
   
   

5. Which statement about vitamin A is most likely true based on its molecular structure? A) It is highly soluble in water due to its polar nature B) It is soluble in fat but not in water due to its mostly nonpolar structure C) It is equally soluble in both water and fat D) It cannot dissolve in any solvent
   
   

6. A solution that contains less solute than the maximum amount that can dissolve at a given temperature is: A) Saturated B) Unsaturated C) Supersaturated D) Concentrated
   
   

7. The defining characteristic of a supersaturated solution is: A) It contains less solute than could dissolve at that temperature B) It contains exactly the maximum amount of solute possible at that temperature C) It contains more solute than would normally dissolve at that temperature D) It cannot dissolve any additional solute regardless of temperature
   
   

8. Molarity (M) is defined as: A) Grams of solute per liter of solution B) Moles of solute per liter of solution C) Moles of solute per kilogram of solvent D) Grams of solute per kilogram of solvent

9. The main difference between dissolution and a chemical reaction is: A) Dissolution always involves a color change B) Dissolution is a physical change where the original solute can be recovered C) Chemical reactions involve solids while dissolution involves only liquids D) Chemical reactions are faster than dissolution
   
   

10. A student dissolves 75g of KNO₃ in 100g of water at 60°C. The solution is then slowly cooled to 30°C. Based on the solubility curve, which statement is correct? A) The solution will remain unsaturated at 30°C B) The solution will be exactly saturated at 30°C C) Approximately 30g of KNO₃ will precipitate out of solution D) The solution will become supersaturated unless a seed crystal is added
    
    
    

11. Which intermolecular force is MOST important when explaining why cerium sulfate [Ce₂(SO₄)₃] shows decreasing solubility as temperature increases? A) London dispersion forces B) Ion-dipole interactions C) Hydrogen bonding D) Dipole-dipole interactions
    
    

12. A solution contains both NaCl and KNO₃. If half of the water evaporates, which statement would be true about the resulting solution? A) The solute particles will be twice as concentrated, but the solution will remain unsaturated B) The concentration of both solutes will remain unchanged C) One salt might precipitate while the other remains dissolved, depending on their relative solubilities D) Both salts will precipitate in proportion to their original concentrations