Chemistry Concepts Worksheet

Which of the following best describes the difference between heat and temperature?

• Heat is a measure of the total energy of molecular motion in a substance, while temperature is a measure of the average energy of molecular motion.

• Heat is a measure of the average energy of molecular motion, while temperature is a measure of the total energy of molecular motion in a substance.

• Heat and temperature are the same and can be used interchangeably.

• Heat is a measure of the energy required to change the state of a substance, while temperature is a measure of the energy required to change its temperature.

Answer explanation

The correct choice highlights that heat refers to the total energy of molecular motion, while temperature measures the average energy of that motion. This distinction is crucial in thermodynamics.

Thermodynamics is defined as the branch of physics that deals with the relationships between heat and other forms of energy.

• True

• False

Answer explanation

True. Thermodynamics indeed studies the relationships between heat and other forms of energy, making the statement accurate.

Energy is defined as the ability to do work. What are the two types of energy?

• Kinetic and Potential

• Thermal and Nuclear

• Electrical and Chemical

• Magnetic and Gravitational

Answer explanation

The two main types of energy are Kinetic and Potential. Kinetic energy is the energy of motion, while Potential energy is stored energy based on position. These concepts are fundamental in understanding energy in physics.

What is the first law of Thermodynamics?

• Energy cannot be created or destroyed, only transformed.

• Entropy of an isolated system always increases.

• For every action, there is an equal and opposite reaction.

• The total energy of a system remains constant.

Answer explanation

The first law of Thermodynamics states that energy cannot be created or destroyed, only transformed. This means that the total energy in a closed system remains constant, aligning with the correct choice.

What’s the relationship between 1 calorie and joules? Hint -> this is also the specific heat of water

• 1 calorie = 4.184 joules

• 1 calorie = 3.5 joules

• 1 calorie = 4.2 joules

• 1 calorie = 5 joules

Answer explanation

1 calorie is defined as the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius, which is equivalent to 4.184 joules. Therefore, the correct relationship is 1 calorie = 4.184 joules.

Define System. a. Whats an Open system? b. Whats a closed system? c. Whats an isolated system?

• A system where energy and matter can be exchanged with the surroundings.

• A system where only energy can be exchanged with the surroundings, not matter.

• A system where neither energy nor matter can be exchanged with the surroundings.

Answer explanation

An open system allows both energy and matter to be exchanged with the surroundings, making it the correct choice. In contrast, closed systems exchange only energy, while isolated systems exchange neither.

Define Surroundings.

• The area around a particular place

• A type of plant

• A mathematical equation

• A historical event

Answer explanation

The correct definition of 'Surroundings' refers to 'The area around a particular place', which encompasses the environment or context surrounding a specific location.

What is Specific Heat, C? -> amount of heat required to raise temp of 1.0g substance 1ºC

• The amount of heat required to raise the temperature of 1.0g of a substance by 1ºC

• The amount of heat required to raise the temperature of 1.0kg of a substance by 1ºC

• The amount of heat required to raise the temperature of 1.0g of a substance by 10ºC

• The amount of heat required to raise the temperature of 10g of a substance by 1ºC

Answer explanation

Specific heat, C, is defined as the amount of heat required to raise the temperature of 1.0g of a substance by 1ºC, making the first answer choice correct.

What is Enthalpy, H? -> Heat content a. What is Δ H? -> Change in Enthalpy (measurable)

• Enthalpy, H, is the heat content of a system, and Δ H is the measurable change in enthalpy.

• Enthalpy, H, is the pressure of a system, and Δ H is the measurable change in pressure.

• Enthalpy, H, is the volume of a system, and Δ H is the measurable change in volume.

• Enthalpy, H, is the temperature of a system, and Δ H is the measurable change in temperature.

Answer explanation

The correct choice states that Enthalpy, H, is the heat content of a system, which aligns with its definition in thermodynamics. Δ H represents the measurable change in this heat content during a process.

Endothermic is a reaction which ___. -> requires energy a. Is Δ H positive or negative?

• requires energy a. Is Δ H positive or negative?

• releases energy a. Is Δ H positive or negative?

• does not involve energy change a. Is Δ H positive or negative?

• requires energy b. Is Δ H positive or negative?

Answer explanation

Endothermic reactions require energy to proceed, which means they absorb heat. This results in a positive ΔH, indicating that the enthalpy of the products is greater than that of the reactants. Thus, the correct choice is 'requires energy a.'.