1. (TCO 7) (a) Given that the molar mass of H 3 PO 4 is 97.994 grams/mol , deter
ID: 883345 • Letter: 1
Question
1. (TCO 7) (a) Given that the molar mass of H3PO4 is 97.994 grams/mol , determine the number of grams of H3PO4 needed to prepare 0.75 L of a 0.25 M H3PO4 solution. Show your work. (5 points)
(b) What volume, in liters, of a 0.25 M H3PO4 solution can be prepared by diluting 50 mL of a 2.5 M H3PO4 solution? Show your work. (5 points)
2. (TCO 7) (a) What is the volume percentage of a solution prepared by dissolving 30 g of NaOH in enough water to make a final volume of 120 mL? Show your work. (5 points)
(b) How many mL of a 10% solution can be made from the solution in part a? Show your work. (5 points)
3. (TCO 12) Discuss how the structures of HDPEs, LDPEs, and LLDPEs contribute to their use (3 points each). Provide an example of a product produced by each product (2 points each). (5 points for each polymer type) (Points : 15)
4. (TCO 11) Tungsten (W), with a mass number of 180 and an atomic number of 74, decays by emission of an alpha particle. Identify the product of the nuclear reaction by providing its atomic symbol (5 points), mass number (5 points), and atomic number (5 points). (Points : 15)
5. (TCO 6) A sample of helium gas occupies 1,021 mL at 719 mmHg. For a gas sample at constant temperature, determine the volume of helium at 745 mmHg. Show your work. (Points : 5)
Explanation / Answer
I am supposed to answer only 1 question at a time. So I will answer question 1 for you. please ask other questions separately again.
Question 1:
a)
Volume, V = 0.75 L
Molarity, M = 0.25 M
Number of moles = M*V
= 0.25*0.75
=0.1875 mol
Molar mass = 97.994 gram/mol
so,
mass = number of moles * Molar mass
= 0.1875 * 97.994
=18.37 gm
Answer: 18.37 gm
b)
Use dilution formula:
Mi*Vi = Mf*Vf
2.5*50 = 0.25 * Vf
Vf = 500 mL
Answer: 500 mL or 0.5 L