Conservation of Mass Practice Test

A balanced chemical reaction obeys the law of

• ideal gases

• definite proportions

• conservation of matter

• conservation of energy

Tags

NGSS.MS-PS1-5

Balance the chemical equation

• Na + Cl2 ---> NaCl

• 2Na + Cl2 ---> NaCl

• 2Na + Cl2 ---> 2NaCl

• 2Na + 2Cl2---> 2NaCl

Tags

NGSS.MS-PS1-5

Describe the mass of the reactants and products given the balanced chemical reaction

• The mass of the products is 2/3 that of the reactants

• The mass of the reactants equals the mass of the products

• The mass of the reactants is less than the mass of the products

• The mass of the reactants is greater than the mass of the products

Tags

NGSS.MS-PS1-5

The law of conservation of matter states that during a chemical reaction, the amount of matter

• increases

• decreases

• disappears

• stays the same

Tags

NGSS.MS-PS1-5

Explain why the model of this chemical reaction obeys the Law of Conservation of Matter

• because there are the same number of atoms of each element shown on both sides

• because they both start and end with diatomic (two-atomed) molecules

• because they both start and end with the same types of particles

• because they both start and end with two sets of particles

Tags

NGSS.MS-PS1-5

20g of sugar is stirred into a beaker containing 100 g of water. After the sugar has completely dissolved, the solution is put on the scale. What is the mass of the solution?

• 20 g

• 80 g

• 100 g

• 120 g

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Mrs. Smith is demonstrating a chemical change for her class. She places 15 grams of baking soda into a beaker. Next she adds 15 grams of vinegar to the same beaker. When the two compounds make contact, they bubble and fizz a great deal. She places the beaker on the balance and notes that the mass of the solution in the beaker is less than the expected 30 grams. Explain why the mass of the solution in the beaker is less than 30 grams

• the balance was not working correctly

• the gas that was released changed the mass

• mass is always lost in a chemical reaction

• the new products have less mass than the original reactants

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

"After some wood has completely burned in a fire, some of the matter that made up the wood has been destroyed."

Is the statement correct or incorrect? Explain.

• It is correct. The ashes weigh less than the original wood and this proves that some of the mass was destroyed.

• It is incorrect. Ashes look different than wood but the mass of the ashes is the same as the mass of the original wood.

• It is incorrect. Look at the ashes under the microscope. These particles will look exactly like the particles in the wood.

• It is incorrect. Capture and collect all of the gases given off by the fire and combine these masses with the mass of the left over ashes. This should equal the mass of the original wood.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Compare the illustration above with the choice below. Which picture best represents the outcome according to the law of conservation of matter?

• 
• 
• 
• 

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

A flask with vinegar in it has a mass of 160 grams. A balloon with baking soda in it has a mass of 40 grams. The balloon is attached to the flask to seal the opening and the vinegar and baking soda mixes. The balloon inflates to a large volume. What will the total mass of the balloon and flask be after the balloon inflates? Explain.

• Less than 200 grams because the solid baking soda disappears

• 200 grams, because all the atoms remain in the balloon or flask

• More than 200 grams because the size of the balloon is so much larger

• Less than 200 grams because gases such as the one in the balloon are lighter than solids and liquids

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2