Chemistry, 11.03.2020 02:39 wendybhenry61391

When a 5.00 g sample of KBr is dissolved in water in a calorimeter that has a total heat capacity of 3.10 kJ ⋅ K − 1 , the temperature decreases by 0.270 K . Calculate the molar heat of solution of KBr .

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Answer from: springcoates

19.9J/mol

Explanation:

Using the law of conservation of energy, the heat of solution of KBr equals the heat absorbed or released by the calorimeter.

In this case, the temperature of the calorimeter decreased, then it released heat that the sample of KBr absorbed. This is, then, an endothermic change.

The heat released by the calorimeter equals its heat capacity multiplied by the change in temperature:

Heat released = 3.10 kJ . K⁻¹ × 0.270 K = 0.837J

Then:

Heat absorbed by the sample of KBr = 0.837J

The molar heat of solution is the heat absorbed by the sample divided by the number of moles in the sample.

Convert 5.00 g of KBr into number of moles

number of moles = mass in grams / molar massnumber of moles = 5.00g / 119.002 g/mol = 0.042016 mol

Divide the heat absorbed by the number of moles

Molar heat of solution = 0.837J / 0.042016 = 19.92 J/mol

You must round to 3 significant figures: 19.9J/mol ← answer

Answer from: Quest

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

Write 15 uses of a mercury barometer along with its characterestics

Answer from: Quest

i'm pretty sure its b i might be wrong though!

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When a 5.00 g sample of KBr is dissolved in water in a calorimeter that has a total heat capacity of...

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