Chemistry exam
Which of the following statements is incorrect?
Increase in temperature of a system favors an exothermic reaction
When energy is transferred to a body as heat, its internal energy
Increases
An exothermic reaction
Is accompanied by evolution of heat
Is the study of energy changes that occur during chemical reactions and during changes of state
Thermochemistry
The study of energy changes that occur during chemical reactions is called _____.
thermochemistry
An unknown mass of aluminum requires 6290 joules to raise the temperature from 23.9ºC to 80.0°C. What is the mass of the aluminum? The specific heat of aluminum is 0.900 J/g∙°C
125g
The specific heat of liquid water is _____ Jg ∘C.
4.18
Which observation(s) would immediately indicate that an exothermic reaction has occurred?
A reaction glows bright with light. A reaction feels spontaneously hot.
Which statement is TRUE about the relationship between heat and temperature in reactions?
A reaction that releases heat will feel warmer
Which statement(s) is/are TRUE about combustion reactions?
ALL combustion reactions are exothermic. Combustion reactions release energy in the form of heat.
The breaking of chemical bonds _____ energy, while the forming of bonds _____ energy.
Absorbs, releases
Which of the following could cause an object's temperature to rise?
All of the above
Which statement about the chemical reactions of photosynthesis is true
All of the above
Given the table above, which of the following has the highest specific heat?
Ammonia
Compared to the particles in a liquid lava sample, the particles in a hardened lava sample
Are moving slowly
Which of the following are example(s) of an endothermic reaction or process?
Both A or B
Chemical energy is the stored in ___________ bonds
Chemical
Thermochemistry is the study of the relationship between heat energy and...
Chemical energy
A cup of hot water is placed next to a cup of cold water. After a while, the temperatures of water in both cups are equal. What kind of system does this describe?
Closed system
If heat is absorbed by the system from the surroundings in a chemical reaction or physical change, it is called an process.
Endothermic
Complete the sentence using one of the following words light, energy, or radiation. Besides matter, all chemical reactions require _____ in order for the reaction to occur.
Energy
After a certain reaction, it is determined that the total energy of the products is higher than the total energy of the original reactants. What happened with energy in the reaction
Energy was absorbed from the surroundings
After a certain reaction, it is determined that the total energy of the products is lower than the total energy of the original reactants. What happened with energy in the reaction?
Energy was released into the surroundings
Water is a(n) ______ coolant for machinery and engines because of its _____ specific heat
effective; high
Which of the substances in the table above would rise in temperature the fastest if equal masses of all were subjected to the same heat input?
gold
Give the general equation for an exothermic reaction.
reactants → products + energy
You have a 20 gram piece of aluminum and a 40 gram piece of aluminum sitting in the sun. Which piece will warm by ten degrees first?
20 gram aluminum
Which observation would indicate that an endothermic reaction has occurred?
A reaction starts to feel cold on its own.
Which of the following best describes how energy can be written in chemical equations for exothermic reactions?
Energy can written as a product on the right side of the arrow since it is being released.
Which of the following systems can exchange matter?
Open system
Which process(es) below are likely to be endothermic
Storing energy in chemical bonds. Melting ice into liquid water
Which of the following reactions is exothermic?
Two of the above
The heat required to raise the temperature of 12 g of water from 16°C to 21°C is:
60 cal
Which statement is TRUE about the relationship between heat and temperature in reactions?
A reaction that absorbs heat will feel colder
Which of the following is/are true
Both a and b
The amount of heat required to raise the temperature of one gram of water by one degree Celsius is a _____
Calorie
Which of the following best describes how energy can be written in chemical equations for endothermic reactions
Energy can be written as a reactant on the left side of the arrow since energy is being absorbed in the reaction
Which statement(s) is/are TRUE about energy and exothermic reactions?
Energy is involved in ALL chemical reactions. Some energy is released in the course of all chemical reactions. A reaction is exothermic if more energy is released than absorbed by the reaction.
In a chemical reaction or physical change, if heat is released by the system into the surroundings the process is referred to as
Exothermic
A book sitting on a high shelf falls to the floor. What best describes the energy conversion during the fall?
Gravitational potential energy is converted to kinetic energy
An exothermic reaction is a process in which the reacting substances
Have more energy than the products
Which type of energy is transferred between the two objects due to the temperature difference between them?
Heat
All energy must be accounted for in every physical or chemical process. This is a statement of the
Law of Conservation of Energy
The two basic types of energy are:
kinetic energy and potential energy
The addition of heat causes the individual particles of a solid to
Vibrate more rapidly
Does heat flow from the region of higher temperature to the region of lower temperature?
Yes
Which relationship between chemical bonds and energy is observed in an exothermicreaction?
More energy is released by forming new bonds in the products than is required to break bonds in the reactants
Which relationship between chemical bonds and energy is observed in an endothermicreaction?
More energy is required to break bonds in the reactants than is released by forming new bonds in the products.
An open glass of water is placed on the table. After a while, the temperatures and volume of the water are both altered. What kind of system does this describe?
Open system
What is the relationship between energy and temperature in endothermic reactions?
Products have higher energy than reactants, but the temperature at the end is lower
What is the relationship between energy and temperature in exothermic reactions?
Products have lower energy than reactants, but the temperature at the end is higher.
Which statement(s) is/are TRUE about energy and endothermic reactions?
Some energy is absorbed in the course of all chemical reactions. Chemical reactions ALWAYS involve energy. A reaction is endothermic if more energy is absorbed than released by the reaction
Thermal equilibrium is attained when two objects have the same..
Temperature
In a reaction between barium hydroxide and ammonium chloride
The energy stored in the bonds of the products is larger compared to the energy stored in the bonds of the reactants
Which of the following can be said in the crystallization of liquid salt
The energy stored in the bonds of the products is smaller compared to the energy stored in the bonds of the reactants
You have a 10 gram piece of aluminum and a 10 gram piece of gold sitting in the sun which receive the same heat input over time. Which metal will warm by ten degrees celsius first?
The gold will warm by 10°C first.