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2 years ago

Calculate ΔH∘f (in kilojoules per mole) for benzene, C6H6, from the following data:

1 answer:

7 0

ΔH for the reaction = [sum of heat of formation for products] - [sum of heat of formation for reactants]

-6534 = [(12)(-393.5) + (6)(-285.8)] - (2X)

-6534 = [(-4722) + (-1714.8)] - 2X

-6534 = -6436.8 - 2X

-6534 + 6436.8 = -2X

-97.2 = -2X

then, divide each side by two to cancel out the numerical coefficient.

x = +48.6 kJ, which is the heat of formation for benzene.

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A bicycle pump contains 20 cm3 of air at a pressure of 100 kPa. The air is then pumped in a tyre of volume 100 cm3. Calculate th

Natasha2012 [34]

Answer:

The pressure of the air in the tyre is 20 kPa

Explanation:

The parameters for the bicycle pump and tyre are;

The volume of air contained in the bicycle pump, V₁ = 20 cm³

The pressure of the air contained in the bicycle pump, P₁ = 100 kPa

The volume (available) of the tyre, where the air is pumped, V₂ = 100 cm³

Let P₂ represent the pressure in the tyre after the air is pumped

By Boyle's law, we have that at constant temperature, the volume of a given mass of gas is inversely proportional to its pressure;

Mathematically, Boyle's law gives the following equation;

P₁ × V₁ = P₂ × V₂

∴ P₂ = (P₁ × V₁)/V₂

Substituting the known values gives;

P₂ = (100 kPa × 20 cm³)/(100 cm³)

∴ P₂ = 100 kPa × 1/5 = 20 kPa

P₂ = 20 kPa

The pressure of the air in the tyre = P₂ = 20 kPa.

7 0

2 years ago

A student is trying to calculate the density of a can. He already knows the mass, but he needs to determine the volume as well.

elena-14-01-66 [18.8K]

Answer:

V=Bh

Explanation:

B h is used for rectangular solids and cylinders

6 0

3 years ago

A shot-putter accelerates a 7.2 kg shot from rest to 17 m/s . what work did the shot-putter do on the ball?

garri49 [273]

1.0x10^3 Joules The kinetic energy a body has is expressed as the equation E = 0.5 M V^2 where E = Energy M = Mass V = Velocity Since the shot was at rest, the initial energy is 0. Let's calculate the energy that the shot has while in motion E = 0.5 * 7.2 kg * (17 m/s)^2 E = 3.6 kg * 289 m^2/s^2 E = 1040.4 kg*m^2/s^2 E = 1040.4 J So the work performed on the shot was 1040.4 Joules. Rounding the result to 2 significant figures gives 1.0x10^3 Joules

6 0

3 years ago

A small flashlight bulb provides a resistance of 3 Ω to the 300 mA current that runs through it. Determine the voltage of the ba

Contact [7]

V=IR

V= 0.3 x 3

V= 0.9V

3 0

3 years ago

Which type of reaction is this? CH3COOH + H20 2 H+ + CH3C00

kumpel [21]

Answer:

dissociation of acetic acid (like vinegar) in water

Explanation:

CH3COOH is basically vinegar (aka acetic acid)

dissociation of acetic acid in water

so when you put vinegar in water it makes 2 hydrogen ions (H+) and acetate ( CH3C00 ) a chemical that used in making film

8 0

2 years ago