CHEM 120 Week 8 Final Exam /(100% Correct)

1. (TCO 8) 35.0 mL of 0.25 M NaOH is neutralized by 23.6 mL of an HCl solution. The molarity of the
t t t t t t t t t t t t t t t t t t t t t



HCl solution is (show your work): (Points : 5)
t t t t t t t t t t
tttttt


molarity = moles solute / liters solution
0.25 M = moles NaOH / 0.035 L
moles NaOH = 0.00875 moles NaOH


tttttt t


0 1644446450 Short 1

2. (TCO 1) How many mL are in 3.5 pints? Show your work. (Points : 5)
tttttt
t t t t t t t t t t t t t t t t




3.5 pints is equivalent to 1656.116

1 pint = 473.176 ml
3.5 pints* 473.176mL = 1656.116mL

tttttt t


0 1644446452 Short 6

3. (TCO 3) What is the name of the following compound: Zn3P2? (Points : 5)
tttttt
t t t t t t t t t t t t t t t




It's Zinc Phosphide




tttttt t


0 1644446453 Short 7

4. (TCO 3) What is the name of the following compound: AgNO3? (Points : 5)
tttttt
t t t t t t t t t t t t t t t




Silver nitrate




tttttt t


0 1644446454 Short 11

5. (TCO 6) Calculate the pressure, in atmospheres, of 2.78 mol CO(g) in a 4.25 L tank at 51 degrees C.
t t t t t t t t t t t t t t t t t t t t



(Points : 5)
t
tttttt
t t t




Given that n = 2.78 mol; V = 4.25 L; and temperature

[2.78 mol* 0.0821 L -atm/ mol-K*304 K)/4.25 L = 16.3


tttttt t


0 1644446456 Short 14
t



6. (TCO 6) A gas at a temperature of 95 degrees C occupies a volume of 165 mL. Assuming constant
t t t t t t t t t t t t t t t t t t t



pressure, determine the volume at 25 degrees C. Show your work. (Points : 5)
t t t t t t t t t t t t t t t



Answer:
tttttt



Using Charles’ Law, (V1/T1) = (V2/T2).
tttttt t t t t t t



First, convert temperature to KELVIN (T1 = t1 +273)
t t t t t t t t t



Thus, T1 = 95 + 273 = 368. t t t t t t t t




We have V1 (165 mL) & T2 = (25 + 273) = 298.
t t t t t t t t t t t t t



V2 = (V1*T2)/T1 = (165 mL*298)/368 = 133.6 mL.
t t t t t t t t tt

, 0 1644446457 Short 16

7. (TCO 6) A sample of helium gas occupies 1021 mL at 719 mmHg. For a gas sample at constant
t t t t t t t t t t t t t t t t t t t



temperature, determine the volume of helium at 745 mmHg. Show your work. (Points : 5)
t t t t t t t t t t t t t t t t



Answer:
ttttt



1021mL * 719 mm/745 mmHg = 985.36mL =985mL
ttttt t t t t t t t t




Using Boyle’s law, P1V1 = P2V2. We have V1 (1021 mL), P1 (719 mmHg) and P2 (745 mmHg).
t t t t t t t t t t t t t t t t t



0 1644446459 Short 19

8. (TCO 12) If one strand of a DNA double helix has the sequence T T A G C G A C G C, what is the
t t t t t t t t t t t t t t t t t t t t t t t t t t



sequence of the other DNA strand? (Points : 10)
t t t t t t t t t t



Answer:
tttttt



AATCGCTGCG t t t t t t t t t




1. (TCO 7) (a, 5 pts) Given that the molar mass of H3PO4 is 97.994 grams, determine the number of
t t t t t t t t t t t t t t t t t t t



grams of H3PO4 needed to prepare 0.75L of a 0.25M H3PO4 solution. Show your work.
t t t t t t t t t t t t t t t t


(b, 5 pts) What volume, in Liters, of a 0.25 M H3PO4 solution can be prepared by diluting 50 mL of a
t t t t t t t t t t t t t t t t t t t t t



2.5M H3PO4 solution? Show your work. (Points : 10)
t t t t t t t t t t



tttttttttttt Answer:
Using the molar mass given, convert this amount to grams.
mass = 0.1875 mol * (97.994 g/mol) = 18.37 grams H3PO4

b. M1*V1 = M2*V2
w here: M1 = 0.25; V1 = ??; M2 = 2.5; V2 = 50 mL = 0.050 L
Solvig for V1:
0.25 * V1 = 2.5 * 0.050
V1 = 0.50 L

2. First convert the given mass of NaOH to volume (in mL) using the density of NaOH
Volume = 43 g * (1 mL/2.13 g) = 20.19 mL

Volume % = (volume of solute / volume of solution) * 100%
Volume % = (20.19 mL/120 mL) * 100% = 16.8 %

b. Volume % = volume of NaOH/ total volume
0.10 = 20.19 mL/total volume
Solving for total volume yields:

tttttt t


0 1644446463 Essay 3

2. (TCO 7) (a, 5 pts) What is the volume percent of a solution prepared by dissolving 21 g of NaOH in enough
t t t t t t t t t t t t t t t t t t t t t t



water to make a final volume of 120 mL? Show your work.
t t t t t t t t t t t t t


(b, 5 pts) How many mL of a 10% solution can be made from the solution in part a? Show your work.
t t t t t t t t t t t t t t t t t t t t t



t (Points : 10) t t t



Answer:
tttttttttttt

, Part 1: based on the density of NAOH =2.1g/mL

then calculate the volume of 21g NaOHx(1mL/2.1g)=10 mL

so the percent volume is defined as

% volume = (Volume of Solute/volume of solution) x 100

so w e have % volume = (10mL/120mL)x100=8.3%

Part 2: you cannot prepare 10 % (volume) from the above solution (8.3%)
because the final solution is more concentrated than the initial




tttttt t


0 1644446464 Essay 5
t


0 1644446466 Essay 7

4. (TCO 11) Tungsten (W), with a mass number of 180 and an atomic number of 74, decays by
t t t t t t t t t t t t t t t t t t



t emission of an alpha particle. Identify the product of the nuclear reaction by providing its atomic
t t t t t t t t t t t t t t t



t symbol (5 pts), mass number (5 pts), and atomic number (5 pts). (Points : 15)
t t t t t t t t t t t t t t t



tttttttttttt Answer:
mass of 180 becomes 176

atomic number of 74 becomes 72

name: Hafnium
Symbol: Hf




tttttt t


0 1644446467 Essay 11
t


0 1644446469 Essay 14

6. (TCO 13) What is the mRNA sequence for the following segment of DNA:
t t t t t t t t t t t t t t



--AAACGTGTGCTAACA-- (10 pts)? Based upon the mRNA sequence, what is the peptide sequence
t t t t t t t t t t t t


(10 pts)?
t t



(Points : 20) t t t



Answer:
tttttttttttt