Final Exam Jeopardy!

Conversions

100

A chemist needs 457.8 g of KMnO4 to make a solution. How many moles of KMnO4 is that?

457.8gKMnO4×(1molKMnO4/158.04gKMnO4)=

2.897 mol KMnO4

200

How many moles of Na2CO3 are in 10.0 mL of a 2.0 M solution?

M = moles of solute / liters of solution

2.0 M = x / 0.0100 L <--- note the conversion of mL to L

x = 0.020 mol

300

How many Kelvins are in -15.5 oC

-15.5 oC + 273 = 258K

400

Calculate the number of oxygen atoms and its mass (g) in 50 g of calcium carbonate

calcium carbonate, CaCO3

Molecular mass of CaCO3= 40+12+3×16 = 100 

50g(1mol/100g)(3molO/1molCaCO3)(6.022x10^23atoms/1mol) = 9.033×10^23 atoms 

Mass of Oxygen atoms = 1.5mol O × 16g/1mol = 24 g

500

How many moles of Na are needed to make 4.5 liters of a 1.5 M Na solution?

A solution of molarity 1.5 M, requires 1.5 mol of Na to every liter of solution.

M=mol/L

4.5L requires 6.75 mol of Na, as 

4.5(L)x1.5(mol/L)=6.75 (mol)

Periodic table

100

Which one of the following classifications is incorrect?(a) H2O(s), molecular solid

(b) C4H10(s), molecular solid

(c) KF(s), ionic solid

(d) SiC(s), covalent solid

(e) S(s), metallic solid

Which one of the following classifications is incorrect?(a) H2O(s), molecular solid

(b) C4H10(s), molecular solid

(c) KF(s), ionic solid

(d) SiC(s), covalent solid

(e) S(s), metallic solid

200

Describe the important periodic trends

300

Knowing that the electron configuration of Al is [Ne] 3s² 3p¹, what is the charge of this ion?

3+

400

Explain the difference between the copper in the following compounds:

copper (II) sulfate

copper (I) sulfate

Write the equations for each.

Cu+2, Cu+1

copper (II) sulfate CuSO4

copper (I) sulfate Cu2SO4

500

Which has the lowest boiling point considering molecular size and inter molecular forces?

(a) HF

(b) HCl

(c) HBr

(d) HI

(e) H2SO4

Which has the lowest boiling point?

(a) HF (b) HCl (c) HBr(d) HI(e) H2SO4

Between HCl molecules only small dispersion

HCl < HBr < HI < HF

(If you increase molecular weight, you increase the london dispersion and boiling point as in the order of HCl, HBr, and HI. And HF has the highest boiling point because it has H bonds)

Thermochemistry

100

What are the units expressed for ΔH° rxn?

kJ/mol

200

What is the most stable form (ΔH°=0) of carbon's allotropes (diamond and graphite)? 

graphite

300

You find that the air trapped in a tube occupies 35.5 cm3 at 2.34 atm. By adding mercury to the tube, you increase the pressure on the trapped air to 3.45 atm. Assuming constant temperature, what is the new volume of air (in L)?  

You find that the air trapped in a tube occupies 35.5 cm3 at 2.34 atm. By adding mercury to the tube, you increase the pressure on the trapped air to 3.45 atm. Assuming constant temperature, what is the new volume of air (in L)?  

Solved:

P1V1=P2V2

35.5 cm3 x (1 mL/1 cm3) x (1 L/1000 mL)= 0.0355 L

0.0355L(2.34atm)=V2(3.45atm)     

Solve for V2

V2=0.0241 L

400

Calculate ΔH° for the reaction:

Na2O(s) + SO3(g) --> Na2SO4(g) given the following information:

1. Na(s) + H2O(l) --> NaOH(s) + 1/2 H2(g) 

ΔH°(1)=-146 kJ

2. Na2SO4(s) + H2O(l) --> 2NaOH(s) + SO3(g) 

ΔH°(2)=+418 kJ

3. 2Na2O(s) + 2H2(g) --> 4Na(s) + 2H2O(l)

ΔH°(3)=+259 kJ

(1) x2 = -292

(2) flip = -418

(3) x 1/2 = 129.5

-581 kJ

500

Calculate ΔH° rxn for the following: 

CH4 (g) + 2O2 (g) ---> CO2 (g) + 2H2O(l) 

and the following values are given:

(ΔH° f CH4= -75 kj/mol, ΔH° f O2= 0 kj/mol, ΔH° f CO2= -394 kj/mol, ΔH° f H2O= -284 kj/mol) 

Is this an endothermic or exothermic reaction?

ΔH° rxn = [1 mol xΔH° f (CO2 ) +2 mol x ΔH° f (H2O)]-[1 mol x ΔH° f (CH4)]

−887 kJ/mol exothermic

Equations

100

Balance the following equation:

Pb(NO3)2 (aq) + NaCl (aq)→NaNO3 (aq) +PbCl2 (s)

Pb(NO3)2 (aq)+2NaCl (aq)→2NaNO3(aq)+PbCl2(s)

200

What do the coefficients in the following equation represent?

Na2S + 2AgI → 2NaI + Ag2S

mols, molecules

300

Write the net ionic equation for 3CuCl2(aq)+2K3PO4(aq)→6KCl(aq)+Cu3(PO4)2(s)

total: 3Cu2+(aq)+6Cl−(aq)+6K+(aq)+2PO3−4(aq)→6K+(aq)+6Cl−(aq)+Cu3(PO4)2(s)

net: 3Cu +2(aq)+2PO4 -3(aq)→Cu3(PO4)2(s)

400

Group the following into Strong Acids vs Weak Acids: 

HF, CH3COOH, H2SO4, H3PO4, HCl

WEAK: HF, CH3COOH (Carboxylic acids are weak), H3PO4

STRONG: H2SO4, HCl

500

2 NaCl + Pb(NO3)2 --> 2 NaNO3 + PbCl2

How many grams of lead (II) chloride are produced from the reaction of 15.3 g of NaCl and 60.8 g of Pb(NO3)2? What is the limiting reactant?

LR-->NaCl

36.4 g PbCl2 is produced

bonus points: 17.4 g Pb(NO3)2 will be left over/excess

Electron

100

How many (sigma bonds/pi bonds) are in a double bond? And how about a single bond?

Can you explain each type of bonding?

double bonds have one σ and one pi (π) bond

single bonds consist of one sigma (σ) bond

sigma (end to end, stronger), pi (side to side, weaker)

Note: as the bond strength increases, the bond length decreases. Thus, we find that triple bonds are stronger and shorter than double bonds between the same two atoms; likewise, double bonds are stronger and shorter than single bonds between the same two atoms.

200

Assign oxidation numbers to the atoms in the following ion

SO4 2-

SO42- 

(+6) + 4(-2) = -2

300

Describe each inter molecular force from strongest to weakest

ion-dipole, hydrogen bonding, dipole-dipole, and dispersion force

400

What is the valence bond hybridization of the central atom in each of the following?

(a) BeH₂

(b) PO₃^-4

What is the valence bond hybridization of the central atom in each of the following?

(a) BeH_{2   linear, sp}

(b) PO₃^-4 _{tetrahedral, sp3}

500

List every single element in the periodic table that exists diatomically 

*hint: remember a certain mnemonic device?