Chemical Reactions

What is the Law of Conservation of Mass?

• It states that energy can be created or destroyed in a chemical reaction.

• It states that matter cannot be created or destroyed in a chemical reaction.

• It states that mass can change but energy remains constant in a chemical reaction.

• It states that all chemical reactions require a change in temperature.

What does it mean to balance a chemical equation?

• To ensure that the number of atoms of each element is the same on both sides of the equation, reflecting the conservation of mass.

• To increase the speed of a chemical reaction by adding more reactants.

• To change the physical state of the reactants and products involved in the reaction.

• To determine the energy changes that occur during a chemical reaction.

What happens to atoms during a chemical reaction?

• Atoms are destroyed to form new substances.

• Atoms get rearranged to form new substances.

• Atoms remain unchanged during the reaction.

• Atoms combine to form larger atoms.

What is a chemical reaction?

• A process in which substances (reactants) undergo a transformation to form new substances (products).

• A method of mixing chemicals without any change in their properties.

• A technique used to separate mixtures into their individual components.

• A physical change that alters the appearance of a substance without changing its composition.

What is the balanced equation for the reaction of hydrogen and oxygen to form water?

• H2 + O2 → H2O

• 2H2 + O2 → H2O

• 2H2 + O2 → 2H2O

• H2 + 2O2 → 2H2O

What is the balanced equation for the combustion of methane (CH4)?

• CH4(g) + O2(g) → CO2(g) + H2O(g)

• CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

• CH4(g) + 3O2(g) → 2CO2(g) + 2H2O(g)

• CH4(g) + O2(g) → C(g) + 2H2O(g)

What is the purpose of balancing chemical equations?

• To comply with the Law of Conservation of Mass and accurately represent the quantities of reactants and products.

• To increase the speed of chemical reactions.

• To determine the color of the products formed in a reaction.

• To identify the physical states of the reactants and products.

What is the role of coefficients in a chemical equation?

• Coefficients indicate the number of molecules or moles of a substance involved in the reaction.

• Coefficients represent the temperature at which the reaction occurs.

• Coefficients show the pressure conditions of the reaction.

• Coefficients are used to balance the charges in a chemical equation.

What is the significance of the coefficients in the equation 2H2 + O2 → 2H2O?

• They indicate the number of molecules involved in the reaction.

• They show the temperature at which the reaction occurs.

• They represent the pressure conditions of the reaction.

• They determine the color of the products formed.

What is the difference between a balanced and unbalanced chemical equation?

• A balanced equation has equal numbers of each type of atom on both sides, while an unbalanced equation does not.

• A balanced equation has unequal numbers of atoms on both sides, while an unbalanced equation has equal numbers.

• A balanced equation can only contain one type of atom, while an unbalanced equation can contain multiple types.

• A balanced equation is always a solid, while an unbalanced equation can be a gas or liquid.