Advanced Chemistry Challenge

What is the molar mass of water (H2O)?

• 22.99 g/mol

• 18.02 g/mol

• 20.18 g/mol

• 16.00 g/mol

Define the term 'activation energy' in a chemical reaction.

• Activation energy is the minimum energy needed to initiate a chemical reaction.

• Activation energy is the energy needed to maintain a reaction once it has started.

• Activation energy is the energy required to break chemical bonds after a reaction.

• Activation energy is the total energy released during a reaction.

What is the pH of a neutral solution at 25°C?

• 6

• 7

• 5

• 8

Explain the difference between an ionic bond and a covalent bond.

• Ionic bonds are formed by sharing electrons, while covalent bonds involve ion attraction.

• Covalent bonds involve electron transfer, while ionic bonds are formed by sharing electrons.

• Ionic bonds involve electron transfer and ion attraction, while covalent bonds involve electron sharing.

• Ionic bonds are weaker than covalent bonds and do not involve any electrons.

What is the principle behind Le Chatelier's principle?

• The principle states that a system at equilibrium will remain unchanged regardless of external conditions.

• The principle states that a system will always move towards a state of higher energy when disturbed.

• The principle states that a system at equilibrium will only respond to temperature changes.

• The principle states that a system at equilibrium will adjust to minimize the effect of a change in conditions.

Calculate the number of moles in 50 grams of NaCl.

• 0.75 moles

• 0.5 moles

• 1.2 moles

• 0.855 moles

What is the role of a catalyst in a chemical reaction?

• A catalyst speeds up a chemical reaction by lowering the activation energy.

• A catalyst changes the products of a chemical reaction.

• A catalyst is a substance that is consumed in the reaction.

• A catalyst slows down a chemical reaction by increasing the activation energy.

Describe the process of titration and its purpose.

• Titration is a method for filtering solids from liquids.

• The purpose of titration is to determine the concentration of a solute in a solution.

• The purpose of titration is to mix two solutions until they are the same color.

• Titration is used to measure the temperature of a solution.

What is the difference between an endothermic and an exothermic reaction?

• Endothermic reactions occur only in gases; exothermic reactions occur only in liquids.

• Endothermic reactions absorb heat; exothermic reactions release heat.

• Endothermic reactions release heat; exothermic reactions absorb heat.

• Both endothermic and exothermic reactions absorb heat.

Identify the main types of chemical reactions and provide an example of each.

• polymerization, example: formation of plastics

• neutralization, example: mixing an acid and a base

• The main types of chemical reactions are synthesis, decomposition, single replacement, double replacement, and combustion.

• oxidation, example: rusting of iron