Law of Conservation of Mass

Which BEST represents a balanced equation?

• HgO --> Hg + O₂

• 2Fe + O₂ --> Fe₂O₃

• 2H₂ + O₂ --> 2H₂O

Tags

NGSS.MS-PS1-5

A 14 g sample of Mg reacts with a 12 g sample of S when heated. What mass of MgS is MOST LIKELY produced?

• 2 grams

• 20 grams

• 26 grams

• 168 grams

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Freddy mixed 10 grams of a powdery substance with 200 grams of an acid solution. A bubbly solution weighing 205 grams was formed. Which BEST explains why the mass of the new solution doe not equal the mass of the reactants?

• the other 5 grams changed color

• the other 5 grams created a precipitate

• the other 5 grams were released as gas

• the other 5 grams weighed less in the acid

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which BEST explains why the equation below is NOT balanced?

2Na + H₂O ----> 2NaOH + H₂

• there is too much sodium in the reactants

• there is not enough water in the reactants

• there is too much hydrogen gas in the products

• there is not enough sodium hydroxide in the products

Tags

NGSS.MS-PS1-5

One molecule of CO₂ combines with one molecule of H₂O to make one molecule of carbonic acid. According to the Law of Conservation of Mass, how many atoms of carbon should be in the carbonic acid?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

Which statement is BEST supported by the following equation:

6CO₂ + 12H₂O + light + enzymes ----> C₆H₁₂O₆ + 6O₂ + 6H₂O

• CO₂ is made from the chemical reaction

• No new compounds are made from this reaction

• O₂, oxygen gas, is needed to make the reaction start.

• The atoms rearrange in the chemical reaction so that glucose, C₆H₁₂O₆ is made

Tags

NGSS.MS-LS1-6

What is the total number of oxygen atoms on the product side of the equation below?

CH₃COOH + NaHCO₃ ---> CH₃COONa + H₂O + CO₂

• 2

• 3

• 5

• 7

Tags

NGSS.MS-PS1-5

A piece of paper has a mass of 13 grams. When the paper is burned, a chemical change occurs and both smoke and ashes are produced. Based on the Law of Conservation of Mass, which statement is true?

• the smoke has a mass of 13 grams

• the ashes have a mass of 13 grams

• the smoke and ashes have a combined mass of 13 grams

• the smoke and the ashes have a combined mass less than 13 grams

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which is the BEST system to use when studying the Law of Conservation of Mass?

• a closed system to measure the mass of the reaction

• an open system to measure the mass of the reaction

• a large system to give the reaction space to occur

• a small system to closely observe the reaction

Tags

NGSS.MS-PS1-5

A sealed test tube containing 5 grams of iron fillings and 10 grams of sulfur is heated until the material in the test tube glows bright red. Which is true about the reaction?

• the product will have a mass of 15 grams

• the product will have a mass less than 15 grams

• the product will have a mass more than 15 grams

• the mass of the product cannot be determined

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5