show your work (using dimensional analysis when feasible) No credit for answers

Question

show your work (using dimensional analysis when feasible) No credit for answers only. ing volumes are additive, what is the approximate molarity of a of a solution made by adding 10 mL of ethanol (C2H,O) to 90 mL of water resulting in a solution with a density of 0.9865? 4. What volume (in mL) of a 0.40 M solution of HCI must be added to 500 mL of water to make a 0.25 M solution of HCI? 5. Gaseous ammonia (NH,) gas reacts with HCI gas to form the ionic solid ammonium chloride. a) Write the equation including the "states" of the reactants and products. b) How many grams of HCl gas will react with 10 grams of ammonia. c) If the ammonium chloride produced in b) above is dissolved to make a solution having a volume of 100 mL, what is the molarity?

Explanation / Answer

Q3

molarity = mol / Liter solution

Vtotal = 10+90 = 100 mL = 0.1 L

mass of ethanol = D*V = 0.9865 g/mL * 10 mL = 9.865 g

mol of ethanol = mass/MW = 9.865 /46 = 0.2144 mol

M = mol/V = 0.21440.1 = 2.144 mol

Q4

We need to apply dilution law, which is based on the mass conservation principle

initial mass = final mass

this apply for moles as weel ( if there is no reaction, which is the case )

mol of A initially = mol of A finally

or, for this case

moles of A in stock = moles of A in diluted solution

Recall that

mol of A = Molarity of A * Volume of A

then

moles of A in stock = moles of A in diluted solution

Molarity of A in stock * Volume of A in stock = Molarity of A in diluted solution* Volume of A in diluted solution

Now, substitute known data

M1*v1 = M2*V2

0.4*v1 = 500*0.25

v = 500*0.25/0.4 = 312.5 mL required form stock solution

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.