1. Chapter 6
Chemical Reactions

2. How is a chemical change different than a physical change?
A physical change changes the size, shape, or appearance of the substance. The type of substance does not change.
A chemical change forms a new substance

3. What happens to the atoms/molecules in a chemical reaction?
The atoms of the reactants unbond, rearrange, and then rebond to form new products

4. What is a reactant? What is a product?
A reactant is the substances that are there before the reaction.
A product is what is produced and is there after the reaction.

5. In the chemical equation, where are the reactants located? The products?
The reactants are written on the left side of the equation.
The products are written on the right side of the equation

6. What is the law of conservation of mass/matter?
The law states that the total amount of matter stays the same before and after the reaction.
The type of atoms and the number of atoms is the same on both sides of the chemical equation

7. If you add more reactant why do you get more product?
The more reactant has more atoms to react and form more product

8. You mix baking soda and vinegar
You mix baking soda and vinegar. The more baking soda you add, the more of a reaction you will have. When does the reaction stop?
The reaction will stop when you have used all of either the baking soda or vinegar.

9. If you continue to add more baking soda, will the reaction continue forever?
No, the reaction will only continue until there is no more vinegar left to react with the baking soda. (You will have extra baking soda on your product side)

10. What is the evidence that a chemical reaction occurred?
Change in:
Color
Sound
Forms a gas
A precipitate is formed
Temperature change
light

11. When does a precipitate form?
When 2 liquids react and a solid is formed

12. What does a catalyst do?
It speeds up the reaction

13. Each substance is unique in how it reacts with other substances
Each substance is unique in how it reacts with other substances. What does this mean?
A substance will always react the same way when tested with the same chemical. This is called a characteristic property.

14. What type of reaction increased the temperature of the mixture?
Exothermic reaction

15. If 2 substances react and the temperature decreases, what type of reaction occurred?
Endothermic reaction

16. Where is more energy used in an exothermic reaction?
The temperature increases, so more energy is released when the bonds in the products are formed than is used to break the bonds in the reactants.

17. Where is more energy used in an endothermic reaction?
The temperature decreases, so more energy is needed to break the bonds of the reactants than is released when the bonds in the products are formed.

18. In a sample of water, there are always some water molecules which have become ions. How are these ions produced? What are the ions?
A proton is transferred from one water molecule to another.
These ions are H3O+ and OH-

19. When the pH of water is neutral, there are how many H3O+ and OH- ?
Equal amounts of each

20. When the pH of water is basic, there are how many H3O+ and OH-
When the pH of water is basic, there are how many H3O+ and OH- ? When it is acidic?
Basic: more OH-
Acidic: more H3O+

21. What happens to the number on the pH scale when a substance is more basic? More acidic?
Basic: number is higher (more blue/purple)
Acidic: number is lower (more red/orange)

22. How can you neutralize a solution?
If it is basic, slowly add an acid
If it is acidic, slowly add a base

23. According to the Law of Conservation of Mass/Matter, no new atoms are __________ or ____________.
Created
destroyed

24. If you increase the amount of reactants, you may increase the amount of ___________.
products

25. Products are usually formed more quickly at __________ temperatures.
higher

26. Does a catalyst become part of the products of a chemical reaction?
No, they just speed up the reaction.

27. Can you tell by how 2 substances react what they are?
YES, because substances have specific characteristics in how they react.

28. What does it take to break bonds? To form bonds?
Energy
energy

29. Are 2 molecules more likely to react if they have more energy when they collide?
Yes, there’s more energy to break or create bonds

30. In a combustion reaction, is matter destroyed?
No, based on the law of conservation of mass, no matter/mass is ever destroyed or created.
The type and number of atoms is equal on both sides of the equation

31. Can atoms that are not in the reactants end up in the products of a chemical reaction?
Atoms that are NOT in the reactants cannot end up in the products because the products are only made up on the atoms of the reactants.

32. CO4 + O2 CO2 + H2O Balance this equation
It is already balanced!
There is 1 carbon, 4 hydrogen, 4 oxygen on each side of the equation

33. When you combined calcium chloride solution with a baking soda solution, a precipitate formed. How is this evidence that a chemical reaction occurred?
A new substance was formed. This new substance is different than the 2 substances with which you started.

34. A glowstick works when 2 chemicals in the glowstick mix and have a chemical reaction that produce products and light. Why does a warm glowstick glow brighter than a cold glowstick?
In the warm glowstick the molecules in the reactants are moving faster, so they interact faster. Reactants have to collide with each other to start the reaction.

35. Your teacher added universal indicator solution to substances in 2 different cups. The indicator turned a different color in each cup. Explain how you know the substances in the 2 cups must have been different.
Substances react chemically in characteristic ways. If the same test liquid resulted in 2 different colors, then the substances must have been different substances.

36. What is a solvent? A solute?
Solvent does the dissolving
Solute is what dissolves into the solvent

37. Describe the 4 types of chemical reactions:
Synthesis: combining of two or more elements or compounds
Decomposition: when a compounds breaks apart
Replacement: when one element replaces another in a compound
Combusion: when fuel (containing carbon) reacts with oxygen to make water and CO2