physical & chemical changes
Rotting food and fizzing are signs of what kind of reaction? AND how do you know?
Chemical: color change, sound produced, gas produced
Convert 34.5 moles of Carbon to mass of carbon
34.5 mol x 12.011g/mol = 414.38 grams
OR
34.5 mol x 12g/mol = 414 grams
Would you rather have a head the size of an orange or the size of a watermelon?
Orange: +200
Watermelon: -100
What kind of reaction is
HCl + KOH --> H2O + KCl
acid-base
HCl = acid
KOH = base
The H2O formed comes from each molecule
How many electron shells does Magnesium have?
Mg is in Period 3, which means it has 3 electron shells
oOoOh are you nervous?
Yes, and you should be: -200
No, liars!: -400
What is greatest in mass: 23.5 moles of aluminum, 15.7 moles of titanium, or 11.7 moles of copper?
23.5 mol Al = 632.15 g
15.7 mol Ti = 750 g
11.7 mol Cu = 742.9 g
How many neutrons does Chlorine have?
Neutrons = Mass - Protons
35g/mol - 17 = 18 Neutrons
Balance:
N2 + H2 --> NH3
N2 + 3H2 --> 2NH3
What are 3 metalloids?
Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium
Chemical or Physical?
KNO3(s) --> K+(aq) + NO3-(aq)
Physical -- it dissolved
Are you willing to take the risk??
Yes: +300
No: +100
Baking soda has a pH of 8.5 and bleach has a pH of 12. What does this mean about them?
Both are bases, but bleach is more basic.
When ionic compounds are added to water, they dissolve. This is a physical change. If you were to read a chemical equation, what would you see that tells you a compound has dissolved?
The symbol would be (aq), which stands for aqueous
NaCl(s) + H2O(L) = Na(aq) + Cl(aq) + H2O(L)
What are two properties of the elements in group 17?
1) Nonmetals
2) Highly reactive
3) Have 7 valence electrons
4) High electronegative (meaning they like to steal electrons from others)
CH4(g) + 2O2 --> CO2(g) + 2H2O(g) + 245KJ
Chemical or physical? What does KJ stand for and what does it tell you?
Chemical, KJ = kilojoules, which tells you the reaction releases heat
2Fe + 3H2SO4 --> 1Fe2(SO4)3 + 3H2
If 3.5 moles of Iron Sulfate were produced, how many moles of Sulfuric Acid did you start with?
3.5 x 3/1 ratio = 10.5 mol H2SO4
Nitrogen has the electron configuration 1s22s22p3. What is the electron configuration for the element with atomic number 11?
1s22s22p63s1
Sodium!
State this equation aloud:
AgI + Na2S --> Ag2S + NaI
Silver Iodide + Sodium Sulfide --> Silver Sulfide + Sodium Iodide
Would you rather have gold or silver jewelry?
Gold: +300
Silver: +400
A group of chemistry students were conducting a lab to investigate the the change that takes place when potassium chlorate (KClO3) gets heated and decomposes. They noticed that when the reaction is completed, the mass of the products have decreased. What do you think causes this decreased mass? Extra 300 pts if you can name the products!
KClO3 decomposes into KCl and O2. Because a gas is formed, the mass on the scale has decreased as the oxygen has escaped into the air.
2Fe + 3H2SO4--> 1Fe2(SO4)3 + 3H2
This reaction started with 10g Fe. How many grams of H2 were released?
10g Fe x 1mol/55.85g = 0.179 mol Fe
0.179 x 3/2 (ratio) = 0.269 mol H2
0.269 mol H2 x 2g/1mol = 0.537g H2
What is the formula for ammonia sulfate?
(NH3)2SO4
NH3 has a +1 charge and SO4 has a -2 charge
Write and balance the equation:
Iron (III) Oxide + Carbon(s) --> Fe(s) + CO2
2Fe2O3 + 3C --> 4Fe + 3CO2
Why are Group 17 and Group 1 elements highly reactive?