Balancing Chemical Reactions Notes

Multiple Choice

Is milk going sour a physical or chemical change?

• Physical 
• Chemical

Multiple Choice

Is copper tarnishing a physical or chemical change?

• Physical 
• Chemical

Labelling

Label the reactants and products in the chemical equation shown.

Drag labels to their correct position on the image

Products

Reactants

Hotspot

Click on the products coefficient.

Multiple Choice

What does the coefficient in a chemical equation represent?

• The number of atoms in a molecule

• The number of each substance needed

• The state of matter of each substance

• The total mass of the reactants

Open Ended

Explain why it is important to balance chemical equations and describe the consequences of not doing so.

Multiple Select

Which of the following statements about subscripts and coefficients in chemical equations are correct?

• Subscripts can be changed to balance equations

• Coefficients tell us the number of each substance needed

• Coefficients can be changed but subscripts cannot

• Subscripts represent the state of matter

Multiple Choice

Which step in balancing equations involves changing the coefficients only on either side of the equation to balance the number of each atom?

• Write the equation for the reaction

• Put the symbols of each element in a column

• Count the number of each atom on both sides

• Change the coefficients only

Multiple Choice

In the equation 2Na(s) + Cl2(g) → 2NaCl(s), what does (g) indicate about chlorine?

• It is a solid

• It is a liquid

• It is a gas

• It is aqueous

Multiple Choice

Which of the following is NOT evidence of a chemical change?

• Release of light

• Temperature change

• Odor change

• Change in shape

Multiple Choice

Which of the following best describes the role of reactants in a chemical reaction?

• They are the substances that are produced in the reaction.

• They are the starting substances that undergo change.

• They are the catalysts that speed up the reaction.

• They are the substances that remain unchanged.

Open Ended

Reflecting on today's lesson about physical and chemical changes, what is one example from your daily life where you have observed a chemical change?