Activity No. 1.2
Consider activity guides no. 1 and 2. Study first the given table and scenario.
Table 1: Boiling point of two liquid samples
Temperature in 'c
SAMPLES
Before After 5 After 8 After 10 After 12 After 14 After 16
heating minutes minutes minutes minutes minutes minutes
28
40
65
90
100 100 100
Liquid A
45
30
65
Liquid B
97
105
108
113
Scenario 1: Melting point of two solid samples
Chef Matt and his assistant observed two solid samples: Solid A and Solid B.
Both substances are white crystalline powder. They cannot determine which is a
substance and mixture just by looking at it. So, to distinguish which is which, they
heated the two samples using an improvised melting dish. Both the two samples
were heated at the same time and received an equal amount of heat. After a few
minutes, they had observed that Solid A melts completely within a short period of
time; while Solid B has portions that seem to be not melting,
To find out if you have understood the important concepts of the lesson,
ariswer the following questions below.
1. Which liquid sample is a pure substance?
Table 1: Boiling point of two liquid samples
Samples Ternperature Observation while heating
Liquid A
Liquid B
2. Which solid sample is a pure substance?
Scenario 1: Melting point of two solid samples
Samples Appearance Observation while melting
Solid A
Solid B
During boiling, the temperature of a substance changes at the start then it
becomes the same and constant. During melting, a substance melts completely/
smoothly within a short time.
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Answer:
liquid A temp:100
liquid B temp:113
observation while heating liquid A:has lower melting point than liquid B
observation while heating liquid B:has higher melting point than liquid A
* The pure substance in this situation is liquid B
Solid A Appearance: white crystalline powder
Solid B Appearance: white crystalline powder
Observation while melting solid A: Solid A melts completely within a short period of time
Observation while melting solid B: Solid B has portions that seem to be not melting
*The pure substance in this situation is Solid A
Explanation: