Question

26. You are provided with a 250 mL volumetric flask, deionized water and solid NaOH. a) How much NaOH should be weighed out in order to make 250. mL of 0.100 M solution? (5points) b) You have deionized water, the mass of sodium hydroxide found in part a and the volumetric flask. In what order and how much of the two substances, water and NaOH, do you add to the flask? ( 4 points) i) First you add _______________ (amount) of _____________ (substance) to the volumetric flask. ii) Second you add _________________ (amount) of _____________ (substance) to the volumetric flask. 29.During a titration, a sample of 0.2500 M H2SO4 was completely neutralized by 35.0 mL of 0.1000 M NaOH. What volume of H2SO4 was used in the titration? H2SO4 (aq) + 2 NaOH (aq)Na2SO4 (aq) + 2H2O (l) a) 28.0 mL b) 7.00 mL c) 25.0 mL d) 21.0 mL e) 14.0 mL 38.A piece of copper (Cu) metal at 100.0 0C was dropped into 50.0 g of water at 20.0 0C in a calorimeter. The final temperature of the water was 22.6 0C. What was the mass of the Cu metal? Specific heat of Cu = 0.38 J/g0C Specific heat of water = 4.18 J/g0C. Neglect any heat loss to the calorimeter. a) 18 g b) 21 g c) 550 g d) 543 e) Not enough information

Answer 1

a) How much NaOH should be weighed out in order to make 250. mL of 0.100 M solution? (5points)

M = 0.1 M

V = 250 mL = 0.25 L

mol = MV = 0.25 *0.1 = 0.025 mol of NaOH required

mass = molMW = 0.025*40 = 1 g of NaOg required

b) You have deionized water, the mass of sodium hydroxide found in part a and the volumetric flask. In what order and how much of the two substances, water and NaOH, do you add to the flask? ( 4 points)

i) First you add 250 mL (amount) of water (substance) to the volumetric flask.

. ii) Second you add 1 g (amount) of NaOH (substance) to the volumetric flask.