Question

B.ANALYSIS OF AN UNKNOWN ACID

TRIAL 1

a)Mass of bottle +unknown = 108.41g

b)Mass of bottle = 108.1917g

c)Mass of unknown used = 0.22g

d)Final buret reading = 13.1ml

e)Initial buret reading =0ml

f)mL of NaOH used =13.1ml

g)Mass of KHP in unknown=______?

h)Percent of KHP in unknown=______?


TRIAL2

a)Mass of bottle +unknown = 97.616g

b)Mass of bottle = 97.42g

c)Mass of unknown used = 0.196g

d)Final buret reading = 23.2ml

e)Initial buret reading =13.1

f)mL of NaOH used =13.1ml

g)Mass of KHP in unknown=______?

h)Percent of KHP in unknown=______?


TRIAL3

a)Mass of bottle +unknown = 111.9953g

b)Mass of bottle = 111.7953g

c)Mass of unknown used = 0.20g

d)Final buret reading = 33.0ml

e)Initial buret reading =23.2ml

f)mL of NaOH used =9.8ml

g)Mass of KHP in unknown=______?

h)Percent of KHP in unknown=______?

●Calculate Average Percent of KHP =_________?

●Standard deviation=_________?

Answer 1

Trial 1

moles of NaOH used = moles of KHP

moles of NaOH used = (Volume of NaOH used)*(Concentration of NaOH)

You have not specified a concentration, so be it, concentration of NaOH = 0.05 mol/L. If the concentration is different, it must be replaced.

moles of NaOH used = (0.0131 L)*(0.05 mol/L) = 0.000655 moles

moles of NaOH used = moles of KHP = 0.000655 moles

mass of KHP in unknown = moles of KHP*(FW of KHP) = (0.000655 moles)*(204.2212 g/mol) = 0.1338 g KHP

% KHP in unknown = (mass KHP in unknown)*100%/weight of unknown

= (0.1338g/0.22g)*100% = 60.82 %

Trial 2

moles of NaOH used = (0.0131 L)*(0.05 mol/L) = 0.000655 moles

moles of NaOH used = moles of KHP = 0.000655 moles

mass of KHP in unknown = moles of KHP*(FW of KHP) = (0.000655 moles)*(204.2212 g/mol) = 0.1338 g KHP

% KHP in unknown = (mass KHP in unknown)*100%/weight of unknown

= (0.1338g/0.196g)*100% = 68.27 %

Trial 3

moles of NaOH used = (0.0098 L)*(0.05 mol/L) = 0.00049 moles

moles of NaOH used = moles of KHP = 0.00049 moles

mass of KHP in unknown = moles of KHP*(FW of KHP) = (0.00049 moles)*(204.2212 g/mol) = 0.1001 g KHP

% KHP in unknown = (mass KHP in unknown)*100%/weight of unknown

= (0.1001g/0.20g)*100% = 50.05 %

Average Percent of KHP = 59.71 %

Standard deviation = 9.46