Homework #2 week one semester two

1. The law of conservation of matter states that atoms cannot be destroyed or created; therefore, all equations must be balanced always.
2. A scientific law is what has been observed and learned from nature.
3. “using up” and “throwing away” are misleading because according to the conservation of matter no atoms can be destroyed because the energy does not get destroyed it just gets transformed into a different substance.
4. Sn + HF becomes SnF₂ + H₂
1. Sn = 1             Sn=1
2. H = 1               H=2
3. F = 1               F = 2
4. This equation is not balanced because there are two Hydrogens and Flurines on the product side but only 1 of each on the reactant side.
5. SiO₂+ C becomes SiC + CO
1. Si = 1              Si = 1
2. O = 2               O = 1
3. C = 1               C = 2
4. The equation is not balanced because the Carbon atoms and the oygen atoms are unbalanced.
6. Al (OH)_3­ + 3 HCl becomes AlCl_3­ + 3 H₂O
1. Al = 1              Al = 1
2. O = 3               O = 3
3. H = 6               H = 6
4. Cl = 3              Cl = 3
5. The equation is balanced
7. N₂ + 3 H₂ becomes 2 NH₃
1. The coefficient of Hydrogen gas is 3
2. The coefficient of NH₃ gas is 2
3. The coefficient of nitrogen gas is 1
8. On paper
9.   1   Ca₃(PO₄)₂ +     3  H₂ SO₄ becomes    2  H₃PO₄ +  3    CaSO₄
1. Ca = 3                                     Ca = 3
2. P = 2                                       P = 2
3. O = 20                                       O = 20
4. H = 6                                       H = 6
5. S = 3                                       S = 3
10.         C₈H₁₈ +  14  O₂ becomes      8    CO₂ +   9    H₂O
1. C = 8                                       C= 8
2. H = 18                                     H = 18
3. O = 2                                       O = 28
11. Na = 2, S = 1, O = 4, K = 2, Cl = 1 becomes Na = 2, Cl = 1, K = 2, S = 1, O = 4
1. The student did not create a balanced equation because all the atoms are conserved properly, yet the student changed the subscripts when the coefficients are the only ones that are supposed to change.
12. ?
13. Molar mass of O₂ = 32, ozone = 48, CaCO_3­ = 100, Mg(OH) ₂ = 58 g, C₉H₈O_4­ = 180
14. The samples can both accurately represent 1 mol of each substance because 1 mol of a substance is a different measurement for each substance because each substance has a different atomic mass (= 1 mol).
15.  If one mole of potassium metal has a mass of 39.1 g:
1. There is 1 atom in 39.1 g potassium
2. There is .5 atoms in 19.55 g potassium
3. There is .1 atom in 3.91 g potassium
4. There is .03 atoms in 1.0 g of potassium