Midterm Review (kind of) AP

a

1

Balance the Equation

__ H3PO4 + ___ Mg(OH)2 --> ___ Mg3(PO4)2 + ___ H2O

2, 3, 1, 6 

2

Determine the empirical formulas for compounds with the following percent compositions:

15.8% carbon and 84.2% sulfur

CS2

3

What are the types of IMF in the compound

HCl

LDF and Dipole-Dipole 

4

Find the oxidation number of C in the compound:

CO

+2 

5

Identify the type of reaction below

HCN + CsOH → CsCN + H2O

Acid/Base
Double Replacement

b

1

2__ H3PO4 + _3__ Mg(OH)2 --> _1__ Mg3(PO4)2 + _6__ H2O

Use the balanced equation from before. How many grams of H3PO4 are there if you have 0.031 moles of Magnesium Hydroxide? 

0.031 Mg(OH)2 * (2/3) * (97.99 g H3PO4/1mole) = 2.03 grams 

2

Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following percent composition: 28.03% Mg, 21.60% Si, 1.16% H, and 49.21% O. The molar mass for chrysotile is 520.8 g/mol.

Mg3Si2H3O8 (empirical formula), 

Mg6Si4H6O16 (molecular formula)

3

Correctly ranks the intermolecular forces of H2O2, N2O4 and NOF in order of Increasing strength.

H2O2 - Hydrogren Bonding

NOF - Dipole-Dipole

N2O4 - LDF

4

Find the oxidation number of Cr in the compound:

Cr2O7 ^ 2-

Cr = +6

5

What compound is the acid?

HCN + CsOH → CsCN + H2O

HCN

c

1

Write the net-ionic equation of the reaction.

2 H3PO4 (aq) + 3  Mg(OH)2 (aq) --> 1 Mg3(PO4)2 (aq) + 6 H2O (l)

 H+ +  OH- -->  H2O (l)

5

What compound is the Base?

HCN + CsOH → CsCN + H2O

CsOH

d

2

2MO(s) + C(s) ---> 2M(s) + CO2(g)

If 5.00 g of an unknown metal oxide (MO) reacted with excess carbon and formed 738 mL of CO2 at 200.0 °C and 0.978 atm, How many moles of CO2 are there? 

Use PV=nRT

n of CO2 = 0.0186 moles 

3

Balance the Equation

__ HCl + __ Na --> __ NaCl + __ H2

2,2,2,1 

4

It takes 83 mL of a 0.45 M NaOH solution to neutralize 235 mL of an HCl solution. What is the concentration of the HCl solution?

0.16 M HCl

5

Balance 

__ NaOH + __ H2SO4 → __ Na2SO4 + __ H2O

2,1,1,2

2NaOH + H2SO4 → Na2SO4 + 2H2O

e

3

What is the limiting reactant? 

2 HCl + 2 Na --> 2 NaCl + H2

Start 13.5 grams HCL

Start with 10.2 grams Na

0.37 mole nacl from hcl

0.44 moles nacl from na

So HCL is the limiting 

5

Use the balanced equation from before

2NaOH + H2SO4 → Na2SO4 + 2H2O

It takes 38 mL of 0.75 M NaOH solution to completely neutralize 155 mL of a sulfuric acid solution (H2SO4). What is the concentration of the H2SO4 solution?

0.092 M H2SO4