CHEM LAB FINAL VS. COLLEGE ALGEBRA FINAL

Percentage Yield and Error

100

Percentage Yield:

1. A reaction with a·calculated yield of 9.23 g produced 7.89 g of product. What is the percent yield for this reaction?

1. 85.5%

200

Percentage Error:

1. An object has a mass of 50 kg. On Sarah's balance, it weights 48 kg. What is the percent error in her balance? 

2. A student measured the temperature of boiling water and got an experimental reading of 94°C. What is the percent error? 

1. 4%

2. 6%

300

Percentage Yield:

1. 5.96 g of ammonia (17.031 g/mol) react completely according to the following reaction:

2NH₃(g) + CO₂(g) ---> CN₂OH₄(s) + H₂O(l)

What is the theoretical yield of urea (CN₂OH₄ 60.056) for this reaction?

2. 9.87 g of ammonia (17.031 g/mol) react completely according to the following reaction: 

2NH₃(g) + CO₂(g) ---> CN₂OH₄(s) + H₂O(l) 

If 13.74 g of urea (CN₂OH₄ 60.056 g/mol) are produced, what is the percent yield for this reaction? 

1. 10.5g

2. 79.0%

400

Percentage Error:

1. The actual volume of an object is 34.8 ml. When Andrew measured it, he obtained the volume as 30.2 ml. What is the percent error in his result? 

2. The time taken by Joseph to prepare a maths worksheet is 30 minutes, which the timer wrongly measured as 38 minutes. What is the percent error in the timer? 

3. The actual volume of a cylinder is 9 cm³. However the volume was wrongly calculated as 8.5 cm³. What is the percent error in the calculation? 

1. 13.21%

2. 26.67%

3. 5.56%

500

Percentage Yield:

1. 85.4 g of chlorine (70.91 g/mol) reacts completely according to the following reaction: 

P₄(s) + 6Cl₂(g) ---> 4PCl₃(I) 

If 104 g of phosphorus trichloride (137.3 g/mol) is produced, what is the percent yield for this reaction? 

2. 15.4 g of methanol (CH3OH 32.042 g/mol) reacts completely according to the following reaction: 

CH₃OH ---> (g) CH₂O(g) + H₂(g) 

If 12.35 g of formaldehyde (30.026 g/mol) is produced, what is the percent yield for this reaction? 

1. 94.5%

2. 85.8%

Logs

100

Find the value of y:

1. log₇ 1/7 = y

2. log_y 32 = 5 

3. log₂ 8 = y 

Answer 1: -1

Answer 2: 2

Answer 3: 3

200

Evaluate:

1. log₃ 1

2. log₇ 7³

3. log₂₅ 5³ 

4. 16^{log4^8} 

1. 0

2. 3

3. 3/2

4. 64

300

Write the following expressions in terms of logs of x, y and z:

1. log x²y 

2. log (x/y)² 

3. log √x³√y²/ z⁴

1. 2 log x + log y 

2. 2 log x − 2 log y 

3.  1/2 log x + 2/3 log y − 4 log z 

400

Exponential and Logarithmic Form:

1. log_1/21/8 = 3 

2. 3^-4 = 1/81 

3. log₆1/36 = −2 

4.√ x = y 

1.  (1/2)³ = 1/8 

2. log₃1/81 = − 4 

3. 6^-2 = 1/36 

4. log_xy = 12 

500

Solve Equations Below:

1. log₉ (x − 5) + log₉ (x + 3) = 1 

2. 6^1-x = 10^x

3. log(3x − 2) = 2 

4. 3^x − 2 = 12 

1. S = { 6 } 

2. S = { 0.438 } 

3. S = {34 } 

4. S = { 2.402 } 

Rational exponents and radicals and General Solubility Rules

100

Write each expression in exponential form:

1. ⁶√10n² 

2. (³√ 3x)² 

1. (10n²)^1/6 

2. (3x)^2/3 

200

Classify each substance as being soluble or insoluble in water:

1. Pbl₂

2. KBr

3. NiCl₂

4. NiCl₂

5. NH₄OН 

1. Insoluble

2. Soluble

3. Soluble

4. Soluble

5. Soluble

300

Write each expression in radical form:

1. (5x)^7/4 

2. (6x)^5/2 

1. (⁴√ 5x)⁷

2. (√ 6x)⁵

400

Show the ions that formed the following compounds: 

1. Zn₃(PO₄)₂ 

2. Al₂S₃ 

3. Iron (III) sulfide 

4. Ammonium cyanide

1. Zn²⁺ and PO₄^3- 

2. Al³⁺ and S^2-

3. Fe₂S₃ - Fe³⁺ and S^2- 

4. NH₄CN - NH⁴⁺ and CN^-

500

Simplify:

1. (81p⁴)^3/2 

2. (16x⁶)^1/2 

1. 729p⁶

2. 4x³

Polynomial Arithmetic

100

Add:

1. (-5x²-x+4) + (-3x²-5x+2)

2. (3x²-2x+1) + (-x²+3x+1)

1. -8x²-6x+6

2. 2x²+x+2

200

Subtract:

1. (-x²+x-4) - (3x²-8x-2)

2. (3x³+3x²+9) - (5x³-7x²+6x-9)

1. -4x²+9x-2

2. -2x³+10x²-6x+18

300

Multiply:

1. 5m²(3m³+5m²-4m+6)

2. (2x+y)(4x-9y)

1. 15m⁵+25m⁴-20m³+30m²

2. 8x²-14xy-9y²

400

Divide:

1. (x²+2x+6) / x

2. (12x²-6x³-3-9x) / (3x-3)

1. x+2+(6/x)

2. -2x²+2x-1-(2/x-1)

500

Multiply and Divide:

1. 2x³(9x²+5y)

2. j³-64 / j-4

3. (x-2)(x²-x+3)

4. (20x²-13x+2) / (5x-2)

1. 18x⁵+10x³y

2. j²+4j+16

3. x³-3x²+5x-6

4. 4x-1

Dilution

100

1.  If you dilute 175 mL of a 1.6 M solution of LiCl to 1.0 L, determine the new concentration of the solution. 

1. x = 0.28 M

Note that 1000 mL was used rather than 1.0 L. Remember to keep the volume units consistent.

200

1. You need to make 10.0 L of 1.2 M KNO₃. What molarity would the potassium nitrate solution need to be if you were to use only 2.5 L of it? 

1. x = 4.8 M 

Please note how I use the molarity unit, mol/L, in the calculation rather than the molarity symbol, M. 

300

1. If I leave 750 mL of 0.50 M sodium chloride solution uncovered on a windowsill and 150 mL of the solvent evaporates, what will the new concentration of the sodium chloride solution be? 

1. 0.63 M 

400

1. If I dilute 250 mL of 0.10 M lithium acetate solution to a volume of 750 mL, what will the concentration of this solution be? 

2. To what volume would I need to add water to the evaporated solution in problem 3 to get a solution with a concentration of 0.25 M? 

1. 0.033 M 

2. 1500 mL

500

1.  To 2.00 L of 0.445 M HCl, you add 3.88 L of a second HCl solution of an unknown concentration. The resulting solution is 0.974 M. Assuming the volumes are additive, calculate the molarity of the second HCl solution. 

2. To what volume should you dilute 133 mL of an 7.90 M CuCl₂ solution so that 51.5 mL of the diluted solution contains 4.49 g CuCl₂? 

3. What is the molar concentration of chloride ions in a solution prepared by mixing 100.0 mL of 2.0 M KCl with 50.0 mL of a 1.50 M CaCl₂ solution? 

1. 1.25 M 

2. V₂ = 1620 mL 

3. 2.33 M