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Chemical Reactions
DHS PS Ch 19 (2018/2019)
Question | Answer |
---|---|
Change of one or more substances converted into new substances describes a ______ ________? | chemical reaction |
Substances that combine or change in a chemical reaction are ____? | reactants |
New substance that are produced in a chemical reaction are called __________? | products |
A law which states that, in a chemical reaction, matter is not created or destroyed; it stays the same is __________? | Conservation of Mass |
What are coefficients? | numbers which represent the number of units of each substance in a reaction |
Knowing coefficients of chemical reactions allowed chemists to do what? | use the correct amounts of reactants to predict the amounts of products produced. |
What is a subscript? | number which represents the number of atoms in a molecule of a particular element |
In a chemical equation what side of the will you find the products? | to the right of the arrow |
In a chemical equation what side will you find the reactants? | to the left of the arrow |
In order for an equation to be balanced, the same number of ____ must be on each side of the equation. | atoms |
Whom is known as the father of modern chemistry? | Lavoiser |
What type of chemical equation has the same number of atoms of each element on each side of the equation? | balanced |
A way to describe a chemical reaction using chemical formulas and symbols is? | a chemical equation |
How many atoms are present in 4 H2O? | 12 |
Ten grams of calcium oxide react to produce 9.3g of calcium and _g of oxygen. What is the mass of the oxygen produced? | 0.7g |
What does it mean for a chemical equation to be balanced? | The same number of atoms of each element is on both sides of the equation. |
Correct coefficient for mercury (II) oxide in the following equation: ___ HgO=> 2Hg+ O2? | 2 |
Why is oxygen written with a subscript 2? | It exists as a diatomic molecule. |
According to the law of conservation of mass, if two atoms of hydrogen are used as a reactant, how many atoms of hydrogen must be part of the product? | 2 |
Show a balanced chemical equation for the synthesis of NaBr from Na and Br2? | 2Na+Br2=2NaBr |
Which reactant correctly balances the following equation: 4Al+ ______=> 2Al2O3? | 3O2 |
Balance the following equation: __ H2SO4+ __ NaNO2=> HNO2+ Na2SO4 | 1,2,2,1 |
An insoluble compound that comes out of solution during a double displacement reaction is called a? | precipitate |
General formulas represents a single-displacement reaction? | A+BC=>AC+B |
What type of reaction is shown in the following chemical equation: NH3+HCl=>NH4Cl? | synthesis |
The formula AB=>A+B represents what type of chemical reaction? | decomposition |
What type of reaction is represented by the following equation: 2H2+O2=>2H2O? | synthesis |
What type of reaction produces a precipitate? | Double displacement |
In a _____ reaction, two or more substances combine to form another substance. | Synthesis |
Which of the following could represent a decomposition reaction? | Compound --> element + element |
Following equation represents what type of chemical reaction: 2H2(g)+ O2(g)-->2H2O(g)? | synthesis |
As a result of the experiments of Lavoisier, you know that in a chemical reaction the mass of the products ______. | Always equals the mass of the reactants |
A substance that speeds up a chemical reaction without being permanently changed itself is a(n)______. | Catalyst |
Rust forming on a car body would be an example of __ __________ ______________? | a chemical reaction |
Substances that prevent, or slow down, chemical reactions are called ____. | Inhibitors |
Symbols in chemical equation means "produces," "yields", or "forms" | --> |
The burning of wood in a campfire that produces heat and light would be both an ______ and an ______ reaction. | Exergonic, Exothermic |
If heat must be added to a chemical reaction for the reaction to take place, the reaction is ______. | Endothermic |
The energy required to break the original bonds is less than engergy released when new bonds form in a(n) | Exergonic |
In a chemical equation, the symbol that means dissolved in water is ______. | (aq) |
The type of reaction that produces more energy than is required is called _____. | Exergonic |
If heat must be added to a chemical reaction for the reaction to take place, the reaction is _____. | Endothermic |
When one element replaces another element in a compound, the reaction is a _____ reaction. | Single-displacement |
The breaking down of a substance into two or more simpler substances is _____. | Decomposition |
Substances that prevent, or slow down, chemical reactions are called _____. | Inhibitors |
A chemical reaction in which heat energy is released is _____. | Exothermic |
According to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactions? | The masses are equal. |
What is an insoluble compound that forms during a chemical reaction? | Precipitate |
A chemical reaction in which two or more substances combine to form another substance is called a _____. | Synthesis reaction |
When most chemical reactions take place, some _____ in the reactants must be broken, a process that requires energy. | Chemical bonds |
The process by which hydrogen and oxygen form water can be classified as a _____. | Synthesis reaction |
TRUE/FALSE: An ice cube melts into liquid water is an example of a chemical reaction. | False |
AB + CD --> AD + CB is an example of a _____ reaction. | Double-displacement |
Why would a catalyst be added to a chemical reaction? | To speed up a reaction |
Some reactions require an input of energy in order to occur. Photosynthesis, the process in which plants use light to make sugars, requires an energy input. This reaction would be classified as _____. | endergonic |
A change in which one or more substances are converted into new substances is called a _____. | chemical reaction |
How would a relationship between reactants and products be shown? | reactants --> products |
What does the law of conservation of mass state? | Matter cannot be created or destroyed, but is conserved. |
According to the law of conservation of mass, if 4 g of O combine with 2 g of H, how many grams of H2O are produced? | 6g |
The symbol (s)used in a reaction stands for a _____. | solid |
The symbol (l) used in a reaction stands for a _____. | liquid |
The symbol (g) used in a reaction stands for a _____. | gas |
The symbol (aq) used in a reaction stands for _____. | aqueous or dissolved in H2O |
What is the function of coefficients in a chemical equation? | They act as unit managers representing the number of units of each substance taking part in a reaction. |
A number below and to the right of a symbol indicating the number of atoms is called a _____. | subscript |
An equation that has the same number of atoms on each side is called a ________. | balanced chemical equation |
Why do we balance chemical equations? | to satisfy the law of conservation of mass |
When balancing chemical equations, you are only allowed to change the _____. | coefficients |
What coefficient is assumed if no coefficient is written before a formula in a chemical equation? | 1 |
The physical forms in which all matter naturally exists, solid, liquid, and gas, are called _____. | states of matter |
This occurs when a substance reacts with oxygen to produce energy in the form of heat and light. | combustion reaction |
What would be an example of a combustion reaction? | whenever something burns : fireworks, candle, campfire, engine, furnace, grill, etc. |
When hydrogen burns in oxygen to form water, this type of reaction occurs. | synthesis |
TRUE/FALSE: When H2O is broken down into hydrogen and oxygen gases, a decomposition reaction takes place. | true |
Most decomposition reactions require the use of _____, _____, or _____. | heat, light, electricity |
When copper wire is placed in a solution of silver nitrate to produce a copper nitrate sloution and silver on the wire, this is an example of a _____ reaction. | single-displacement |
Why do metals such as copper, silver, and gold exist as pure elements? | They are the least active of the metals on the list. |
A _____ reaction occurs when barium nitrate reacts with potassium sulfate to produce barium sulfate and potassium nitrate. | double-displacement |
What type of reaction produces a precipitate? | double-displacement reaction |
A _____ is the force that holds two atoms together. | chemical bond |
Chemical reactions that release energy are called a(n) __________ reaction. | exergonic |
Chemical reactions that release energy, primarily in the form of thermal energy are _____. | exothermic |
A ______ reaction requires energy. | endergonic |
Chemical reactions that require energy in the form of thermal energy are _____. | endothermic |
A _____ is a substance that speeds up a chemical reaction without being permanently changed itself. | catalyst |
A substance used to slow down a chemical reaction is a(n) _____. | inhibitor |
All chemical reactions ______ or _____ energy. | release, absorb |
What are four examples of energy associated with chemical reactions? | thermal, light, sound, & electricity |
A plastic chair breaking down in the presence of sunlight is an _____ reaction. | endergonic (requires light) |
Logs burning in a campfire would be an example of what type(s) of reaction? | exergonic (produces light and sound), exothermic (produces heat) |
A firefly would be an example of _____. | exergonic (produces light) |
An instant cold pack is an example of what type(s) of reaction? | endothermic |
What type of reaction would a hand warmer pack be? | exothermic |
A change in which one or more substances are converted into a new substance is called a(n) _____ reaction. | chemical |
If a precipitate, water, or a gas forms when two ionic compounds in solution are combined, the reaction is a(n) _____ reaction. | double-displacement |
A substance that prevents certain chemical reactions is a(n) _____. | inhibitor |
When two or more substances combine in a chemcial reaction to form another substance, a(n) _____ reaction has taken place. | synthesis |
The breakdown of a substance into two or more simpler substances is a(n) _____ reaction. | decomposition |
In a chemical equation, the substances that react are called _____. | reactant |
A substance that speeds up a chemical reaction without itself being permanently changed is a(n) _____. | catalyst |
A reaction that requires energy in the form of heat is a(n) _____ reaction. | endothermic |
When one element replaces another in a compound, a(n) _____ reaction has occurred. | single-displacement |
If the energy released in a chemical reaction is primarily in the form of heat, that reaction is a(n) ______ reaction. | exothermic |
Numbers in front of the symbols and formulas in an equation are called _____. | coefficients |
If the number of atoms of each element on the left side of an equation is equal to the number of atoms of each element on the right side of the equation, the equation is ______. | balanced |
In a chemical equation, the substances that are produced are called ______. | products |
An insoluble solid that forms when two ionic compounds in solution are combined is a(n) ______. | precipitate |
What is the symbol for a solid? | (s) |
What is the symbol for a gas? | (g) |
What is the symbol for a liquid? | (l) |
What is the symbol for an aqueous solution? | (aq) |
Why is it important to show chemical reactions in a balanced form? | The law of conservation of mass states that matter cannot be created or destroyed so there must be the same mass on both sides. |
The temperature of the beaker holding the reacting substances increased causing a(n) ______ reaction. | exothermic |
The temperature of the beaker holding the reacting substances decreased causing a(n) ______. | endothermic |
Frost formed on the outside of the beaker holding the reacting substances causing a)n) ______. | endothermic |
Name 4 factors that affect reaction rates. | temperature, concentration, volume/pressure, and surface area |
A state in which forward and reverse reactions or processes proceed at equal rates. | equilibrium |
Carbon Dioxide continually escapes and reenters soda is an example of ____________ _______________. | physical equilibrium |
Baking cookies is an example of an ____________ reaction because it requires heat. | endothermic |
The electrolysis of water is an ____________ reaction because it requires electricity. | endergonic |
A chemical reaction inside the abdomen of a firefly produces light is an _______________ reaction. | exergonic |
Coal power plants burn coal to produce energy. This is an example of an ______________ reaction. | exothermic |
Oxidation involves the __________ of electrons. | loss |
Reduction involves the __________ of electrons. | gain |
All combustion reactions require __________ . | oxygen |
The amount of a substance that contains 6.02 x E23 particles of that substance. | mole |
The mass in grams of one mole of a substance is called its ______________ ____________ . | molar mass |
If you increase the temperature of a chemical reaction, the rate of reaction ________________. | increases |
If you increase the concentration of a chemical in a chemical reaction, the rate of reaction ________________. | increases |
If you increase the volume of a chemical reaction, the rate of reaction ________________. | decreases |
If you increase the pressure of a chemical reaction, the rate of reaction ________________. | increases |
If you increase the surface area of a chemical in a chemical reaction, the rate of reaction ________________. | increases |