Summary CHE1503 ASSIGNMENT 1 2025

CHE1503
ASSESSMENT 1
2025

, QUESTION 1




SOLUTION:



Title: Determination of percentage of BaCl2 ∙ 2H2 O in an unknown sample



Aim: To determine the percentage of BaCl2 ∙ 2H2 O in an unknown sample by heating and measuring
the mass loss as a result of dehydration.



Flow diagram:

Obtain hot plate and heat for 5 minutes at 300°C



Place clean, dry evaporating dish on
the hot plate for 5 minutes


Remove dish (with tongs) and cool for 10 minutes on wire mesh


Weigh cooled evaporating dish

Add 1.5 g of sample and record total weight


Heat the sample on the hot plate for 15 minutes


Remove dish, place on wire mesh, and cool for 10 minutes



Weight the dish + residue


Reheat for 15 minutes, then cool for 10 minutes, and reweigh



Calculate weight loss to determine percentage of
sample

, QUESTION 2




SOLUTION:



a).



Chemical equation (eq 3):



CaC2 O4 ∙ H2 O ⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗⃗
200℃ CaC2 O4 + H2 O
i).



Mass of crucible + cover = 28.120 g
Mass of covered crucible + sample = 31.020 g
Mass of covered crucible + sample after heating = 30.141 g



mass(CaC2 O4 ∙ H2 O) = (Mass of covered crucible + sample) − (Mass of crucible + cover)
= 31.020 − 28.120
= 2.900 g


mass(H2 O) = (Mass of covered crucible + sample after heating) − (Mass of covered crucible + sample)



mass(H2 O) = 31.020 − 30.141
= 0.879 g