A student completed an experiment to determine the amount of energy absorbed by a volume of water. The following data were recorded. Mass of beaker: 215.6 g Mass of beaker plus water: 336.1 g Final temperature of water: 71.0°C Energy absorbed: 21.2 kJ What was the initial temperature of the water?

SSCE HSC Chemistry Energy Changes in Chemical Reactions: A student completed an experimen

A student completed an experiment to determine the amount of energy absorbed by a volume of water - HSC - SSCE Chemistry - Question 17 - 2010 - Paper 1

Question 17

A student completed an experiment to determine the amount of energy absorbed by a volume of water. The following data were recorded. Mass of beaker: 215.6 g Mass o... show full transcript

Worked Solution & Example Answer:A student completed an experiment to determine the amount of energy absorbed by a volume of water - HSC - SSCE Chemistry - Question 17 - 2010 - Paper 1

Step 1

Calculate the mass of the water

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Answer

To find the mass of the water, subtract the mass of the beaker from the mass of the beaker plus water:

ext{Mass of water} = ext{Mass of beaker plus water} - ext{Mass of beaker}

So,

ext{Mass of water} = 336.1 ext{ g} - 215.6 ext{ g} = 120.5 ext{ g}

Step 2

Calculate the change in temperature

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Answer

Using the formula for energy absorbed:

Q = mc heta

where

Q is the energy absorbed (21.2 kJ or 21200 J)
m is the mass of the water (0.1205 kg)
c is the specific heat capacity of water, approximately 4184 J/(kg·°C)
θ is the change in temperature (Final temperature - Initial temperature)

Rearranging the formula to find θ gives:

heta = rac{Q}{mc} = rac{21200 ext{ J}}{0.1205 ext{ kg} imes 4184 ext{ J/(kg\cdot°C)}}

Step 3

Calculate final temperature and initial temperature

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Answer

Calculating θ, we have:

heta = rac{21200}{0.1205 imes 4184} = 42.0 °C

Since the final temperature of water is 71.0 °C, we can find the initial temperature:

ext{Initial temperature} = ext{Final temperature} - heta = 71.0 °C - 42.0 °C = 29.0 °C

Step 4

Select the answer

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Answer

Based on the calculated initial temperature, the correct answer is (C) 29°C.

A student completed an experiment to determine the amount of energy absorbed by a volume of water - HSC - SSCE Chemistry - Question 17 - 2010 - Paper 1

Worked Solution & Example Answer:A student completed an experiment to determine the amount of energy absorbed by a volume of water - HSC - SSCE Chemistry - Question 17 - 2010 - Paper 1

Calculate the mass of the water

Calculate the change in temperature

Calculate final temperature and initial temperature

Select the answer

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