Question

1) What kind of acid is the active component in "The Works" toilet bowl cleaner?

2) If 23 ml of 1.4 M NaOH was required to neutralize 10.0 ml of HCl, what is the molarity of the HCl?

3) What volume (in L) of a 2.12 M NaOH solution is required to neutralize 0.16 mol of HCl?

*Remember to report your answer using the proper significant digits

4) A student has finished the titration of a sample of HBr of unknown concentration with 0.2 M NaOH. The student notices small drops of unreacted NaOH were left on the neck of the flask. This means that these drops were dispensed from the buret but were not mixed with the HBr. How will this affect the calculated molarity of the HBr acid?

a)	Cannot be determined
b)	The calculated molarity will be higher than the actual molarity of the unknown.
c)	The calculated molarity will be lower than the actual molarity of the unknown.
d)	This will have no effect on the calculated molarity.

Answer 1

Q1

this is mainly hydrochloric acid at a 9-11% mass concentration

Q2

mmol of base = MV = 1.4*23 = 32.2

ratio is 1:1 so

mmol of acid = 32.2

[HCl] = mmol acid/V = 32.2/10 = 3.22 M

Q3

find V of NaOh for a 0.16 mol of HCl

mol of HCL = 0.16

molof NaOH required = 0.16 mol

then

M = mol/V

V = mol/M

V = 0.16 * 2.12 = 0.3392 L

V = 339.2 mL

Q4

the volume of base will be higher, therefore molarity of HBr will be highier ( incorrectly)

so the concentration will appear to be higher

choose B