Chemical Reactions Level 3 Practice

Which of the following is NOT typically a result of a chemical change?

• A new substance is created.

• A change in color occurs.

• Energy is absorbed or released.

• The original substance can be easily recovered by physical means.

• A change in temperature is observed.

The picture below shows a beaker containing a red liquid with a temperature of 5°C. A BLUE liquid is ADDED to the red liquid. Which of the following pictures provides the MOST evidence that a chemical change has occurred?

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Answer explanation

It has 3 signs of a chemical change: unexplainable color (clear), temperature change, and bubbles (a gas was made).

The part of the reaction shown is called the ---------.

Which of the following chemical equations does not comply with the law of conservation of mass?

• A) 2Na + Cl2 --> 2NaCl

• B) C + O2 --> CO + Li

• C) 2H2 + O2 --> 2H2O

• D) All are correct.

Explain your choice.

In the reaction where hydrogen gas combines with oxygen to form water, which statement is true?

• A) The total mass of water formed is equal to the sum of the masses of hydrogen and oxygen used

• B) The oxygen gas has no mass

• C) The water will weigh less than the oxygen alone

• D) The mass of hydrogen is doubled in the water

If Emma mixes 3 grams of chemical A with 7 grams of chemical B in a science experiment, what is the expected mass of the resulting mixture?

Michael placed 8 grams of ice in a sealed container and left it in a warm room. After the ice melted into water and then evaporated, what is the mass of the water vapor in the container?

• A. 0.0 grams because the state changed

• B. 4.0 grams because liquid water is denser than ice

• C. 8.0 grams because the mass remains constant

• D. It cannot be determined without knowing the room's temperature

Match

• Organelle for Photosynthesis

• Carbon dioxide

• Reactant of Photosynthesis

• Glucose

• Product of Photosynthesis

• Sunlight

• Energy needed for Photosynthesis

• Chlorphyll

Which process indicates a physical change rather than a chemical change?

• Burning

• Rusting

• Decomposing

• Condensing