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aliya0001 [1]
3 years ago
13

How many KJ are given off when 120 grams of water are cooled from 25°C to -25°C?

Chemistry
1 answer:
Pavel [41]3 years ago
4 0

-25.116 Kilojoules  are given off when 120 grams of water are cooled from 25°C to -25°C.

Explanation:

GIVEN THAT:

mass of water = 120 grams OR 0.12 Kg

initial temperature = 25 degrees

final temperature = -25degrees

change in temperature (ΔT) = final temperature - initial temperature

                                          -25 -25

                                        = -50 degrees

specific heat capacity of water = 4.186 joule/gram degree Celsius

Q (heat energy transferred) = ?

Formula used,

Q = mcΔT

    Putting the values in equation

Q = 120 X 4.186 X -50

   =  -25116 joules

The energy in joules is converted to kilo joule by dividing it with 1000.

The negative sign in the energy transfer shows that energy is released in the process.

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Which element has 12 protons 12 neutrons and 12 electrons
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Answer:

Magnesium

Explanation:

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What is the mass (in grams) of 9.44 × 10 to the 24th power molecules of methanol (CH3OH)?
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3 years ago
A reaction is thermodynamically unstable (spontaneous) but no change is observed. The reaction is probably Select the correct an
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Answer:

kinetically stable.

Explanation:

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When we say that a system is kinetically stable, it means that the activation energy or energy barrier for the reaction system is high. Thus reactants are not easily converted into products. The reaction system remains the same for a long while without change.

Finally, when a reaction is thermodynamically unstable (spontaneous) but no change is observed, the reaction is kinetically stable.

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2 years ago
Liquid octane CH3CH26CH3 reacts with gaseous oxygen gas O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O. If 2.80g
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Answer:

54%

Explanation:

The balanced equation is:

2 CH_{3}(CH_{2})_{6}CH_{3} + 25 O_{2} = 16 CO_{2} + 18 H_{2}O

The first step is to determine the limiting reactant. For this, we calculate the moles of each given component and divide the result for the stoichiometric coefficient.

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Percent yield= 0.0398/0.0074 *100 = 54%

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3 years ago
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