Convert between energy units. c. 4.99 × 10³ kJ to kWh

Suppose that a person eats 2105 Calories per day. Convert this amount of energy into each unit. c. kWh

A particular frost-free refrigerator uses about 705 kWh of electrical energy per year. Express this amount of energy in each unit. d. Cal

Which statement is true of the internal energy of a system and its surroundings during an energy exchange with a negative ΔE_sys? a. The internal energy of the system increases and the internal energy of the surroundings decreases. b. The internal energy of both the system and the surroundings increases. c. The internal energy of both the system and the surroundings decreases. d. The internal energy of the system decreases and the internal energy of the surroundings increases.

Identify each energy exchange as primarily heat or work and determine whether the sign of ΔE is positive or negative for the system. a. Sweat evaporates from skin, cooling the skin. (The evaporating sweat is the system.)

Identify each energy exchange as primarily heat or work and determine whether the sign of ΔE is positive or negative for the system. a. Sweat evaporates from skin, cooling the skin. (The evaporating sweat is the system.) b. A balloon expands against an external pressure. (The contents of the balloon is the system.) c. An aqueous chemical reaction mixture is warmed with an external flame. (The reaction mixture is the system.) Identify energy exchanges as primarily heat or work. Determine whether the sign of E is positive or negative for the system.

Identify each energy exchange as primarily heat or work and determine whether the sign of ΔE is positive or negative for the system. Identify each energy exchange as primarily heat or work. a. A rolling billiard ball collides with another billiard ball. The first billiard ball (defined as the system) stops rolling after the collision. b. A book falls to the floor. (The book is the system). c. A father pushes his daughter on a swing. (The daughter and the swing are the system). Identify each energy exchange as primarily heat or work.

A system releases 511 kJ of heat and does 125 kJ of work on the surroundings. What is the change in internal energy of the system?

A system absorbs 225 kJ of heat and the surroundings do 121 kJ of work on the system. What is the change in internal energy of the system?

The air in an inflated balloon (defined as the system) warms over a toaster and absorbs 142 J of heat. As it expands, it does 46 kJ of work. What is the change in internal energy for the system?

We pack two identical coolers for a picnic, placing 24 12-ounce soft drinks and five pounds of ice in each. However, the drinks that we put into cooler A were refrigerated for several hours before they were packed in the cooler, while the drinks that we put into cooler B were at room temperature. When we open the two coolers three hours later, most of the ice in cooler A is still present, while nearly all of the ice in cooler B has melted. Explain this difference.

A kilogram of aluminum metal and a kilogram of water are each warmed to 75 °C and placed in two identical insulated containers. One hour later, the two containers are opened and the temperature of each substance is measured. The aluminum has cooled to 35 °C, while the water has cooled only to 66 °C. Explain this difference.

How much heat is required to warm 2.50 L of water from 25.0 °C to 100.0 °C? (Assume a density of 1.0 g/mL for the water.)

How much heat is required to warm 2.50 kg of sand from 25.0 °C to 100.0 °C?

Suppose that 25 g of each substance is initially at 27.0 °C. What is the final temperature of each substance upon absorbing 2.35 kJ of heat? c. aluminum

An unknown mass of each substance, initially at 23.0 °C, absorbs 1.95 × 10³ J of heat. The final temperature is recorded. Find the mass of each substance.

a. Pyrex glass (T_f = 55.4°C)

b. sand (T_f = 62.1°C)

c. ethanol (T_f = 44.2°C)

d. water (T_f = 32.4°C)

How much work (in J) is required to expand the volume of a pump from 0.0 L to 2.5 L against an external pressure of 1.1 atm?

The average human lung expands by about 0.50 L during each breath. If this expansion occurs against an external pressure of 1.0 atm, how much work (in J) is done during the expansion?

The air within a piston equipped with a cylinder absorbs 565 J of heat and expands from an initial volume of 0.10 L to a final volume of 0.85 L against an external pressure of 1.0 atm. What is the change in internal energy of the air within the piston?

A gas is compressed from an initial volume of 5.55 L to a final volume of 1.22 L by an external pressure of 1.00 atm. During the compression the gas releases 124 J of heat. What is the change in internal energy of the gas?

When 1 mol of a fuel burns at constant pressure, it produces 3452 kJ of heat and does 11 kJ of work. What are ΔE and ΔH for the combustion of the fuel?

The change in internal energy for the combustion of 1.0 mol of octane at a pressure of 1.0 atm is 5084.3 kJ. If the change in enthalpy is 5074.1 kJ, how much work is done during the combustion?

Determine whether each process is exothermic or endothermic and indicate the sign of ΔH. a. natural gas burning on a stove b. isopropyl alcohol evaporating from skin c. water condensing from steam Determine whether each of the following is exothermic or endothermic.

Determine whether each process is exothermic or endothermic and indicate the sign of ΔH. a. natural gas burning on a stove b. isopropyl alcohol evaporating from skin c. water condensing from steam Indicate the sign of ΔH for the following processes.

Determine whether each process is exothermic or endothermic and indicate the sign of ΔH. a. dry ice evaporating b. a sparkler burning c. the reaction that occurs in a chemical cold pack used to ice athletic injuries

What mass of natural gas (CH4) must burn to emit 352 kJ of heat? CH4( g) + 2 O2( g)¡CO2( g) + 2 H2O( g) ΔH °rxn = -802.3 kJ

Nitromethane (CH3NO2) burns in air to produce significant amounts of heat. 2 CH3NO2(l ) + 32 O2( g)¡2 CO2( g) + 3 H2O(l ) + N2( g) ΔH °rxn = -1418 kJ How much heat is produced by the complete reaction of 10.47 kg of nitromethane?

Titanium reacts with iodine to form titanium(III) iodide, emitting heat. 2 Ti(s) + 3 I2( g)¡2 TiI3(s) ΔH °rxn = -839 kJ Determine the mass of titanium that react if 2.38 * 103 kJ of heat is emitted by the reaction.

The propane fuel (C₃H₈) used in gas barbeques burns according to the thermochemical equation: C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(g) ΔH°_rxn = –2044 kJ If a pork roast must absorb 1.6×10³ kJ to fully cook, and if only 10% of the heat produced by the barbeque is actually absorbed by the roast, what mass of CO₂ is emitted into the atmosphere during the grilling of the pork roast?