Chemical Reactions: Practice Questions

When iron filings are mixed with sulfur powder and heated strongly in a test tube, a new substance called iron(II) sulfide is formed. Which of the following statements about this process is correct?

In an experiment, a student mixes 10.0 g of sodium hydroxide solution with 10.0 g of hydrochloric acid in a vacuum-insulated calorimeter. The temperature of the mixture rises from \( 25^{\circ}C \) to \( 32^{\circ}C \). After the reaction, the student evaporates the water to find a white solid residue. Which of the following statements about this process is incorrect?

In an experiment, hydrogen peroxide (\(H_{2}O_{2}\)) decomposes into water and oxygen. The reaction is very slow at room temperature, but happens rapidly when a small amount of manganese(IV) oxide is added. After the reaction, the manganese(IV) oxide is recovered unchanged in mass. What is the role of manganese(IV) oxide and how does it affect the activation energy of the reaction?

In a chemical reaction, the total mass of the reactants is always equal to the total mass of the products. What is this law called?

A student investigates the thermal decomposition of silver oxide (\(Ag_{2}O\)). When the dark brown powder is heated strongly in a test tube, it leaves behind a shiny silver solid and releases a gas. If the student starts with \(4.64\text{ g}\) of silver oxide and the mass of the shiny silver solid remaining is \(4.32\text{ g}\), which of the following statements correctly identifies the gas released and its mass based on the Law of Conservation of Mass?

During Chemical Reactions, what does the Law of Conservation of Mass state regarding the mass of reactants and products?

Explain, in terms of the rearrangement of atoms, why the total mass of the products in the reaction between lead(II) nitrate and potassium iodide solutions is exactly equal to the total mass of the reactants.

A student reacts dilute sulfuric acid with sodium hydroxide solution. The temperature of the mixture rises by \(5^{\circ}\text{C}\). Name the type of chemical reaction occurring and explain the energy change in terms of the system and surroundings.

When methane (\( CH_{4} \)) burns completely in the presence of oxygen, a chemical reaction occurs.

(a) Identify the two products formed in this complete combustion reaction. (2 marks)
(b) Write the word equation for this reaction. (1 mark)

When magnesium ribbon is placed into a test tube containing dilute hydrochloric acid, a chemical reaction occurs and bubbles of gas are observed.

(a) State the name of the gas produced during this reaction. (1 mark)
(b) Describe a simple chemical test to identify this gas. (1 mark)
(c) Write the word equation for this chemical reaction. (1 mark)
(d) If the temperature of the acid is increased, explain what happens to the rate of the reaction. (1 mark)