Unit 3 Post Test: Energy and Changes in Matter

A steel plaque is attached to a block of wood. The steel and the wood have the same mass. After the steel plaque and the wooden block were left outside in the sun for a period of time, both the steel and the wood had increased in temperature, but the steel had a higher temperature than the wood.

It’s possible that the steel plaque had a higher temperature than the wooden block because it absorbed more energy from/released more energy to/was better insulated from its surroundings.

If the steel and the wood received the same amount of energy from the Sun, then the specific heat capacity of the steel must be equal to/greater than/less than the specific heat capacity of the wood.

• absorbs more energy from; less than

• released more energy to; less than

• absorbs more energy from; greater than

• was better insulated from; equal to

Tags

NGSS.HS-PS3-4

A 126.1-gram block of granite at 92.6°C is dropped into a tub of water at 24.7°C in an isolated system.

The final temperature of both the granite and the water is 51.9°C.

The specific heat capacity of granite is 0.795 joules/gram degree Celsius, and the specific heat capacity of water is 4.186 joules/gram degree Celsius.

The granite block transferred 21,500 joules/6,810 joules/4,080 joules of energy, and the mass of the water is 189 grams/55.8 grams/35.8 grams.

• 21,500 joules; 55.8 grams

• 4,080 joules; 35.8 grams

• 6,810 joules; 189 grams

• 4,080 joules; 55.8 grams

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

 $Q=mC\Delta T$ 
 $m\ =\ \frac{Q}{C\Delta T}$  

A kettle of water is at 14.5°C. 
Its temperature is then raised to 50.0°C by supplying it with 5,680 joules of heat. 
The specific heat capacity of water is 4.186 joules/gram degree Celsius. 
What is the mass of water in the kettle? Express your answer to three significant figures.

The mass of the water in the kettle is __________ grams.

Tags

NGSS.HS-PS3-1

 $Given:\ N_2+3H_2\rightarrow2NH_3$  

 $Bond\ :\ Bond\ Energy\ \left(\frac{kJ}{mol}\right)\ \$  
 $N\equiv N\ :\ 942\ \rightarrow H-H\ :\ 432\rightarrow N-H\ :\ 386$  

Express the answer to two significant figures.

Use the bond energies to calculate the change in enthalpy for the reaction.The enthalpy change for the reaction is _______ kilojoules.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS1-4

A man pours some hot coffee into a small cup from a large jug that contains enough coffee for several cups. Which statement correctly compares the coffee in the cup and in the jug?

• The coffee in the cup has a lower temperature than the coffee in the jug because there's less of it.

• The coffee in the cup and the coffee in the mug have the same amount of internal energy.

• The coffee in the jug absorbs more heat than the coffee in the cup because there's more of it.

• The coffee in the jug has more thermal energy than the coffee in the cup.

Tags

NGSS.HS-PS3-4

A student places a 12-gram cube of ice inside a container. After six hours, the student returns to observe the contents of the container. Which sentence suggests that the container is an open system?

• The container contains 8 grams of liquid water and no ice.

• The container contains 12 grams of liquid water and no ice.

• The container contains 8 grams of liquid water and 4 grams of water vapor.

• The container contains 12 grams of ice and no liquid water.

Tags

NGSS.MS-ESS2-4

 $Given:\ CH_4+2O_2→CO_2+2H_2O,\ ΔH=-890kJ/mol$  
Express the answer to three significant figures.

How much energy is released when 59.7 grams of methane (CH4) reacts with oxygen?
The combustion of 59.7 grams of methane releases _______ kilojoules of energy.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS1-4

Which statement best describes the function of enzymes?

• Enzymes reduce the energy of products in biological reactions

• Enzymes reduce the activation energies of biological reactions.

• Enzymes aid biological reactions by removing products quickly.

• Enzymes aid biological reactions by providing more reactants.

Why does every chemical reaction require a certain amount of activation energy?

• Energy is released when the reactants begin to react.

• Energy lost to the environment during the reaction must be replaced.

• The products have more potential energy than the activated complex.

• Forming the activated complex requires energy.

A certain radioactive atom has 90 protons and 142 neutrons. If this atom undergoes alpha decay, what is the mass number of the daughter atom?

The mass number of the daughter atom is _______.

Tags

NGSS.HS-PS1-8