Energy In Chemical Reactions Test

Which describes the enthalpy change associated with an endothermic reaction? It is negative because the enthalpy of the products is greater than the enthalpy of the reactants. It is positive because the enthalpy of the products is greater than the enthalpy of the reactants. It is negative because the enthalpy of the reactants is greater than the enthalpy of the products. It is positive because the enthalpy of the reactants is greater than the enthalpy of the products.

Two metal blocks that have slightly different temperatures are placed next to one another. After five minutes, they both have lower but equal temperatures. According to the law of conservation of energy, what most likely happened? Energy was created inside the blocks. Energy was destroyed inside the blocks. Energy was absorbed into the blocks from outside the system. Energy was transferred from the warmer block to the cooler block.

A welding torch produces a flame by burning acetylene fuel in the presence of oxygen. This flame is used to melt a metal. Which energy transformation represents this process? chemical energy into thermal energy potential energy into kinetic energy kinetic energy into electromagnetic energy potential energy into chemical energy

What explains the key difference between a bomb calorimeter and a coffee cup calorimeter? A bomb calorimeter is 10 times larger but works the same way. A bomb calorimeter measures heat for liquid products only. A bomb calorimeter has a separate chamber to hold substances and can even measure heat gain or loss for reactions that do not occur in water. A bomb calorimeter can measure heat gain or loss in gaseous reactions but is not useful for reactions that occur at high pressures and temperatures.

How should the baking of a pizza be categorized? as an exothermic process because the dough releases heat as an endothermic process because the dough releases heat as an exothermic process because the dough absorbs heat as an endothermic process because the dough absorbs heat

Which statement defines calorimetry? the conservation of energy a unit of energy that is used when calculating energy exchange a device that is used to measure the heat that is gained or lost during a chemical change the measurement of energy that is given off or absorbed in a physical or chemical process

Which statement about enthalpy is true? The enthalpy of formation for a pure element in its standard state is always positive. The enthalpy of formation for a pure element in its standard state is always negative. Enthalpy is a state function because its change depends only on initial and final conditions. Enthalpy is not a state function because its change depends on the identities of the reactants and products.

Which reaction is endothermic? HCl + NaOH NaCl + H2O + 58 kJ 6CO2 + 12H2O + energy C6H12O6 + 6O2 + 6H2O 2Na + Cl2 2NaCl + energy 2C2H6 + 7O2 4CO2 + 6H2O + 2,502 kJ

Which is the best example of how electromagnetic energy is used in everyday life? a pot of boiling water on a gas stove a patient receiving an X-ray in a hospital a car burning gasoline to power the engine a car of a roller coaster moving quickly down a slope

Which direction does thermal energy flow in the following diagram? Heat flows from the ice cream to the hand. Heat flows from the hand to the ice cream. The system is in a state of equilibrium. The system is too cold for heat to move.

Nitrogen dioxide, NO2(g) (Hf = 33.84 kJ/mol), is decomposed according to the following reaction:What is the enthalpy change when 2.50 mol of nitrogen dioxide decomposes? 13.5 kJ of energy released 13.5 kJ of energy absorbed 84.6 kJ of energy released 84.6 kJ of energy absorbed

Which statement best describes the direction of heat flow by conduction between two samples of the same material? Heat flows from faster molecules to slower molecules when they are near. Heat flows from faster molecules to slower molecules when they collide. Heat flows from slower molecules to faster molecules when they are near. Heat flows from slower molecules to faster molecules when they collide.

A metal sample is heated and placed into the water in a calorimeter at room temperature. Which statement best describes how the calorimeter can be used to determine the specific heat capacity of the metal sample? Energy transfers to the metal from the water and calorimeter until they are all at room temperature. Energy transfers from the metal to the water and calorimeter until they are all at room temperature. Energy transfers to the metal from the water and calorimeter until they all reach a single temperature. Energy transfers from the metal to the water and calorimeter until they all reach a single temperature.

Complete combustion of a 0.350 g sample of a compound in a bomb calorimeter releases 14.0 kJ of heat. The bomb calorimeter has a mass of 1.20 kg and a specific heat of 3.55 J/(gi°C).If the initial temperature of the calorimeter is 22.5°C, what is its final temperature?Use . 19.2°C 25.3°C 34.2°C 72.3°C

Which best describes heat? energy that is carried by electric and magnetic fields energy that decreases as a car slows to a stop energy that increases as a book is lifted to a higher shelf energy that flows from a hot mug of tea to a cold hand

Ammonia, NH3 (Hf = -46.2 kJ), reacts with oxygen to produce water (Hf = -241.8 kJ) and nitric oxide, NO (Hf = 91.3 kJ), in the following reaction:What is the enthalpy change for this reaction? Use -900.8 kJ -104.6 kJ 104.6 kJ 900.8 kJ

Manganese dioxide (MnO2(s), Hf = -520.0 kJ) reacts with aluminum to form aluminum oxide (AI2O3(s), Hf = -1699.8 kJ/mol) and manganese according to the equation below.What is the enthalpy of the reaction? -1,839.6 kJ -1,179.8 kJ 1,179.8 kJ 1,839.6 kJ

A generator contains a coil that spins to produce an electric current. How is energy transformed by using a generator? Thermal energy is transformed to potential energy. Thermal energy is transformed to mechanical energy. Chemical energy is transformed to electromagnetic energy. Mechanical energy is transformed to electromagnetic energy.

An ice cube is placed on a kitchen counter. Which best describes heat flow in this situation? Heat flows from the ice to the counter, causing the molecules in the counter to move more quickly. Heat flows from the ice to the counter, causing the molecules in the counter to move more slowly. Heat flows from the counter to the ice, causing the molecules in the counter to move more quickly. Heat flows from the counter to the ice, causing the molecules in the counter to move more slowly.

Which statement is true if the Hrxn of a reaction is positive? The reaction is endothermic. The reaction is exothermic. There is more reactant than product. There is more product than reactant.

The specific heat of water is 4.18 J/(gi°C) and that of wood is 1.97 J/(gi°C). Which statement is correct? Regardless of mass, wood will heat up less than water if the same heat is added. Given equal masses, wood will heat up less than water if the same heat is added. Given equal masses, water will heat up less than wood if the same heat is added. Regardless of mass, water will heat up less than wood if the same heat is added.

Which reaction is endothermic? 2BrCl Br2 + Cl2 + 29.3 kJ 2H2 + O2 2H2O + 572 kJ C + O2 CO2 + 394 kJ N2O4 + 59 kJ 2NO2

Based on the equation and the information in the table, what is the enthalpy of the reaction? Use -453.46 kJ -226.73 kJ 226.73 kJ 453.46 kJ

A student touches a freshly baked cake that was taken out of the oven. Which best explains why the cake feels hot? Molecules in the skin are moving faster than molecules in the cake. Molecules in the cake are moving faster than molecules in the skin. The kinetic energy of molecules in the cake is more than the energy in the baking tray. The kinetic energy of molecules in the baking tray is more than the energy in the cake.

Complete combustion of a 0.600-g sample of a compound in a bomb calorimeter releases 24.0 kJ of heat. The bomb calorimeter has a mass of 1.30 kg and a specific heat of 3.41 J/(gi°C). If the initial temperature of the calorimeter is 25.5°C, what is its final temperature?Use 30.9°C 34.5°C 44.0°C 51.5°C