chem

An endothermic reaction causes the surroundings to: 

• warm up

• become acidic

• condense

• decrease in temperature

• release CO₂

Tags

NGSS.HS-PS1-4

How many calories are in 854.3 J (1 cal = 4.184 J)? 

• 4.9 x 10^-3 cal

• 204.2 cal

• 1.1 x 10^-3 cal

• 0.239 cal

• 3,574 cal

Tags

NGSS.HS-PS3-1

The dissolution of barium hydroxide in water is an exothermic process. Which of the following statements is correct? 

• The enthalpy of solid barium hydroxide plus pure water is less than that of the solution, at the same temperature.

• The enthalpy of solid barium hydroxide plus pure water is greater than that of the solution, at the same temperature.

• The enthalpy of solid barium hydroxide plus pure water is the same as that of the solution, at the same temperature.

• The temperature of the solution is lower than that of the barium hydroxide and water before mixing.

• . When barium hydroxide dissolves in water, the system does work on the surroundings.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Your favorite candy bar, Gummy Beakers, contains 1.2 ´ 10⁶ J of energy while your favorite soft drink, Bolt, contains 6.7 ´ 10⁵ J. If you eat two packs of Gummy Beakers a day and drink 3 cans of Bolt, what percent of your 2000 Calorie daily food intake is left for broccoli, beans, beef, etc. (1 cal = 4.184 J)? 

• . 53%

• 47%

• . 27%

• 11%

• 0%

Tags

NGSS.HS-PS3-1

How many degrees of temperature rise will occur when a 25.0 g block of aluminum absorbs 10.0 kJ of heat? The specific heat of Al is 0.900 J/g·°C. 

• 0.44°C

• 22.5°C

• 225°C

• 360°C

• 444°C

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

A sample of an ideal gas has its volume doubled while its temperature remains constant. If the original pressure was 100 torr, what is the new pressure? 

• 10 torr

• 50 torr

• 100 torr

• 200 torr

• 1000 torr

A sample of N₂ gas occupies 2.40 L at 20°C. If the gas is in a container that can contract or expand at constant pressure, at what temperature will the N₂ occupy 4.80 L? 

• 10°C

• 40°C

• 146°C

• 313°C

• 685°C

Which statement is false? 

• The average kinetic energies of molecules from samples of different "ideal" gases is the same at the same temperature

• The molecules of an ideal gas are relatively far apart.

• All molecules of an ideal gas have the same kinetic energy at constant temperature.

• Molecules of a gas undergo many collisions with each other and the container walls.

• Molecules of greater mass have a lower average speed than those of less mass at the same temperature.

Nitrogen will behave most like an ideal gas 

• at high temperature and high pressure.

• at high temperature and low pressure.

• at low temperature and high pressure.

• at low temperature and low pressure.

• at intermediate (moderate) temperature and pressure.

A flask with a volume of 3.16 L contains 9.33 grams of an unknown gas at 32.0°C and 1.00 atm. What is the molar mass of the gas (R = 0.08206 L atm/mol K)? 

• 7.76 g/mol

• 66.1 g/mol

• 74.0 g/mol

• 81.4 g/mol

• 144 g/mol