Chemical Reactions (Bordelon)

Harrison is making a cake. He prepares batter and places it in the oven. Harrison realizes a gas, carbon dioxide, is coming out of the batter as it bakes. Which options are true about Carbon dioxide?

• It is a new gas that forms during baking

• It is the dough changing state from solid to gas

• It is made of atoms that did not exist before

• It is formed from the atoms of the batter

The element sodium (Na) is a soft solid that will react explosively with water. The element chlorine (Cl) is a toxic gas. When these two elements combine, they produce a stable, crystalline solid known commonly as table salt (NaCl).

How would you explain this?

• When substances combine to form new substances, the properties of the reactants are preserved.

• Sodium and chlorine become different elements during the reaction.

• The properties of each of the two original elements are combined to give salt its properties.

• When substances combine to form new substances, the properties of the resulting substances will be different.

Consider burning a hot cheeto. This is a chemical reaction. The hot cheeto, flame, and oxygen in the air enter a chemical reaction and produce ash and some other things.

Which statement would be true?

• Ash is a different substance than the hot cheeto.

• Ash has similar properties to oxygen.

• The atoms of wood and oxygen disappear during the burning.

• The atoms of the ash did not exist before.

Complete the sentence.

During a chemical reaction, atoms ________.

• can appear

• get rearranged

• can disappear

• stop moving and vibrating

What always happens in a chemical reaction?

• Some atoms of existing substances disappear.

• New atoms appear and form new substances.

• Some substances change phase.

• New substances form from atoms of existing substances.

Identify the product(s) in the following chemical reaction:

Chromium oxide + Carbon → Chromium + Carbon monoxide

• Chromium and carbon.

• Chromium and carbon dioxide.

• Chromium and carbon monoxide.

• Chromium oxide and carbon.

How many silver (Ag) atoms are reactants in this equation?

4Ag + 3O2 → 2Ag2O

• 4

• 3

• 2

• 0

Why are numbers placed before the elements and molecules in a chemical equation?

• To represent if an element or molecule is a liquid, gas, or solid.

• To make sure there's always more reactants than products.

• To balance the equation so that it has the same number of atoms of each element on each side.

• To show whether a substance is an element or molecule.

In chemical reactions, a product is _________.

• any substance that is made of the greatest number of atoms

• any substance that is to the left of the arrow

• any substance that is made from the least number of atoms

• any substance to the right of the arrow

What is the role of the arrow sign in a chemical reaction?

• Making sure atom counts on each side are the same.

• Showing which substances were in the container first and which substances were added later.

• Separating products and reactants.

• Showing which substances are solids and which are liquids or gases.