Test #2 Semester 1 Review

Answer the following questions:

1. Define pH and give examples of an acid, a neutral substance and a base. What pH number will each of these substances have?
- pH is an acidic scale.
- Examples: 1 neutral substance: water 7
                    1 acid: vinegar 1
                    1 base: ammonia 9
(helpful pages 68-70)

2. The speed limit in Canada is 100 km/hr. Convert this to meters/second?
- 360,000,000 meters/second (you get 100,00 which is meters per hour now change it to second so multiply by 60 twice and get your answer!)
(helpful pages see sheet on unit conversion)

3. How many decimal places change when you convert 905 mg to kg? What is the answer?
- 6 decimal places change
- .000905 kg
(helpful pages see sheet on unit conversion)

4. What are the charges and weights of electrons, protons, and neutrons?
- Electrons: -1 (negatively); barely weigh anything
- Protons: +1 (positively); 1 atomic unit
- Neutrons: Neutral 0; 1 atomic unit
(helpful pages see page 38)

5. What is positive, an anion or cation? How is it formed?
- Cation; formed when an element loses an electron.
(helpful pages see page 39)

6. The first column on the periodic table (Na, K, Rb) tend to gain or lose how many electrons and have what charge?
- Lose 1 electron to get a +1 charge
(page 40)

7. The second column on the periodic table (Mg, Ca, Sr) tend to gain or lose how many electrons and have what charge?
- Lose 2 to get a +2 charge.
(page 40)

8. The sixth column on the periodic table (O, S, Se) tend to gain or lose how many electrons and have what charge?
- Gain 2 electrons to get a -2 charge.
(page 40)

9. The seventh column on the periodic table (F, Cl, Br) tend to gain or lose how many electrons and have what charge?
- Gain 1 electron to get a -1 charge.
(page 40)

10. The eighth column on the periodic table (He, Ne, Ar) tend to gain or lose how many electrons and have what charge?
- Don't gain or lose electrons; they are Noble Gases.
(look at the periodic table)

11. Explain and give examples of negative and positive ions?
- Cations and Anions; H+ and O-2
(see pages 39-40)

12. What is an atom compose of?
- Protons, neutrons, and electrons.
(common knowledge)
*molecule > atom > nucleus > proton/neutron > electron

13. Why can't water be 100% pure? What is in even the purest water?
- Impossible to obtain; too expensive; dissolved minerals and gases are always in even the purest water
(common knowledge or see last weeks test study guide)

14. How can we help dissolve more solute in water? (List several ways)
- Raise temperature; heating the water
- Under pressure
- Vigorously stirring; mixing
Example: a lot of CO2 is in coke; coke is under pressure because of the CO2

15. Explain how we know what ionic compounds and the subscripts are formed from K+ and I-. From Ba2+ and OH-. From Al3+ and O2-.
- Kl; Ba(OH)2; Al2O3
- Balancing them
(see Wednesday's quiz)

16. What is the atomic symbol for mercury? What is it's atomic number? Atomic weight? How many protons, neutrons and electrons does it have?
- Hg; 80; 200.59
*Note: atomic number is the top and the weight is the bottom
(see periodic table and page 34)

17. What is an unsaturated versus a saturated solution?
- Unsaturated solution is a solution that contains less dissolved solute than the amount the solvent can hold at a specific temperature while a saturated solution has as much dissolved solute that it can hold at a specific temperature.
(see pages 53-54)

18. Explain how to create a supersaturated solution. Explain the chemistry behind it.
- Unusual term; adding salt as we heat it and then we're cooling it down now that it has a lot of solute and for a short time we can keep a lot of solute in solution more than needed or expected at that lower temperature (unless we jiggle it; just touching it causes it out of solution/precipitate now only some solute is in solution and it goes back to normal).

19. Define the following terms (and explain the Chemistry concepts behind them).

A. Polarity
- When two opposites attract each other.
- Ex. H20-V shaped positive on the bottom end and negative at the top end
(see last tests study guide)

B. Ionic bonds versus covalent (molecular) bonds
- Ionic bonds connect ions and covalent bonds connect molecules. Ionic are not as strong.
NaCl separates in water Na goes to negative side and Cl goes to the other

C. Chemical reaction versus chemical reaction
- Teacher tired.
- Entail the  breaking and forming of chemical bonds, causing atoms to become rearranged into new substances.

D. Reactants versus products
- Reactants are the original (starting) substances in a chemical reaction (written to the left of the arrow), while products are the new substance or substances formed from the rearrangement of the reactant atoms (written to the right of the arrow).

E. Solute vs. solvent vs. solution vs. solubility
- Solute is the dissolved substance (salt is an example)
- Solvent is the dissolving agent (water is an example)
- Solution is a homogeneous mixture of two or more substances
- Solubility is the max quantity of a substance that will dissolve in a certain quantity of water at a specified temperature in water.

F. Unsaturated vs. saturated vs. supersaturated
- Unsaturated: less solute
- Saturated: contains as much solute as possible in the temperature
- Supersaturated: unstable; too much solute

G. Mean vs. Median 
- Mean is the average (adding up all data and then dividing)
- Median is the middle value

H. Chlorine vs. Chloride
- Chlorine is an element
- Chloride is an ion (when it gains an electron)

I. Hydrologic Cycle
- Water gets evaporated to vapor then goes to the the sky and gets precipitated then down back into the ocean. A cycle is a closed system so no water is created or destroyed.

J. Subscript vs. superscript
- Subscript is below the element/compound, superscript is above.

L. Tyndall effect
- The scattering of light indicated that small, solid particles were still in the water. 

M. Catalyst 
- Speeds up the reaction

N. Conservation of matter
- No matter is added or destroyed

20. Chlorine and ozone (O3) are added to water to kill what? 
- Bacteria

21. How would you figure our which is proper ionic formula? McCl vs. MgCl2
- MgCl2 because Magnesium has +2 charge so Cl- needs 2. 
(see Wednesday's quiz)

22. The acidity (or basic-ness) of a substance if measured by ...
- pH

23. How many protons are in each element?
- H: 1
- Mg: 12
- Na: 11
- Cl: 17

24. Explain undissolved solute at the bottom of a beaker of solution?
- The temperature was not high enough
- Not enough pressure
- It was saturated

25. Make up your own question and show it to a neighbor in the class! :)
Ex. Why does the temperature of the solution effect the solubility of the substances?