Describing Chemical Reactions

The expression CaCO3 → CaO + CO2 is an example of a

• reactant.

• product.

• chemical equation.

• chemical progression.

What is the number “4” in SiCl4?

• a subscript

• a coefficient

• a product

• a reactant

The product side of a chemical reaction is shown.

→ 7Ti2(SO4)3

Which number represents a coefficient?

• 2

• 3

• 4

• 7

What can the arrow in a chemical reaction be translated to mean? Check all that apply.

• yields

• accompanied by

• react to form

• added to

• except

Cecil writes the equation for the reaction of hydrogen and oxygen below.

H2 + O2 → H2O

Why does his teacher ask him to balance the equation by including the correct coefficients?

• to show that most molecules exist in pairs

• to show that most compounds exist in pairs

• to show that atoms are conserved in chemical reactions

• to show that atoms are created in chemical reactions

Tags

NGSS.MS-PS1-5

Franklin was performing an experiment by combining hydrochloric acid and sodium hydroxide. He measured the mass of his reactant materials to be 35g. The reaction resulted in the production of salt and water. He reported that his products weighed 32g.

Which best describes the results of Franklin’s experiment?

• No error occurred, some of the products are always lost as heat.

• An error occurred, the mass of the reactants should equal the mass of the products.

• An error occurred, the products should weigh more than the reactants.

• No error occurred, water is not weighed when determining the weight of the products.

Tags

NGSS.MS-PS1-5

Rust results from iron’s reaction to oxygen. An iron nail gains mass when it rusts. How does this reaction support the law of conservation of mass?

• The mass of the rusted nail equals the mass of iron and the oxygen from the air it reacted with to form the rust.

• The mass of the rusted nail increases because iron attracts more protons from the air.

• The increased mass of the rusted nail is an exception to the law of conservation of mass since the rusted nail’s mass increases.

• The increased mass of the rusted nail results from the rearrangement of protons and neutrons within oxygen, according to the law of conservation of mass.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which best represents the law of conservation of mass?

• mass of reactants > mass of products

• mass of reactants < mass of products

• mass of reactants = mass of products

• mass of reactants → mass of products

Tags

NGSS.MS-PS1-5

Liquid 1 reacts with Liquid 2, producing a solid and a gas. Using this scenario, which supports the law of conservation of mass?

• mass of Liquid 1 + mass of solid = mass of Liquid 2 + mass of gas

• mass of Liquid 1 – mass of solid = mass of Liquid 2 – mass of gas

• mass of Liquid 1 – mass of Liquid 2 = mass of solid + mass of gas

• mass of Liquid 1 + mass of Liquid 2 = mass of solid + mass of gas

Tags

NGSS.MS-PS1-5

For the equation 3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O, how many units of NO3 are represented on the products side?

• 2

• 3

• 6

• 8

Tags

NGSS.MS-PS1-1