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den301095 [7]
3 years ago
11

Is this statement true or false?

Chemistry
1 answer:
Verdich [7]3 years ago
4 0

Answer:

This statement is true.

Explanation:

Palaeontology can be described as the field of science under which the history of the earth is studied. Scientists use fossils to study the history of the earth as they provide evidence for history.

Fossils can be described as the remains of old, dead plants, animals, fungi, prokaryotes which are imprinted on rocks. These imprints provide evidence for the kind of organisms that once inhabited the land. For examples, fossil studies showed the existence of dinosaurs which are now extinct.

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What is the apparent brightness of a star?
Rzqust [24]

Answer:

it's bright where you can see it it's not that bright compared to the sun from Earth it's really not so bright

3 0
2 years ago
When a 0.4500 g sample of impure potassium chloride was dissolved in water and treated with an excess ofsilver nitrate, 0.8402 g
Svetllana [295]

Answer:

97.78% KCl in the original sample

Explanation:

5 0
3 years ago
The vapor pressure of water at 65oC is 187.54 mmHg. What is the vapor pressure of a ethylene glycol (CH2(OH)CH2(OH)) solution ma
Pavlova-9 [17]

Answer:

173.83 mmHg is the vapor pressure of a ethylene glycol solution.

Explanation:

Vapor pressure of water at 65 °C=p_o= 187.54 mmHg

Vapor pressure of the solution at 65 °C= p_s

The relative lowering of vapor pressure of solution in which non volatile solute is dissolved is equal to mole fraction of solute in the solution.

Mass of ethylene glycol = 22.37 g

Mass of water in a solution = 82.21 g

Moles of water=n_1=\frac{82.21 g}{18 g/mol}=4.5672 mol

Moles of ethylene glycol=n_2=\frac{22.37 g}{62.07 g/mol}=0.3603 mol

\frac{p_o-p_s}{p_o}=\frac{n_2}{n_1+n_2}

\frac{187.54 mmHg-p_s}{187.54 mmHg}=\frac{0.3603 mol}{0.3603 mol+4.5672 mol}

p_s=173.83 mmHg

173.83 mmHg is the vapor pressure of a ethylene glycol solution.

6 0
3 years ago
If 8.700 g of c6h6 is burned and the heat produced from the burning is added to 5691 g of water at 21 °c, what is the final tem
leonid [27]
C₆H₆ is benzene which has a molar mass of 78 g/mol. When benzene is burned, the reaction is called combustion. The heat produced in this reaction is called the heat of combustion. For benzene, the heat of combustion is -3271 kJ/mol.

Heat of benzene = (8.7 g)(1 mol/78 g)(-3271 kJ/mol) = -364.84 kJ

By conservation of energy,
Heat of benzene = - Heat of water
where
Heat of Water = mCp(Tf - T₀)
where Cp for water is 4.187 kJ/kg·°C

Thus,

-364.84 kJ = -(5691 g)(1 kg/1000 g)(4.187 kJ/kg·°C)(Tf - 21)
<em>Tf = 36.31°C</em>
8 0
3 years ago
Determine the overall energy change for the reaction between hydrogen and oxygen shown in Question 13. Use Figure 2.
zimovet [89]

Answer:

–500KJ

Explanation:

Data obtained from the question include the following:

Heat of reactant (Hr) = 800KJ

Heat of product (Hp) = 300KJ

Enthalphy change (ΔH) =..?

The enthalphy change is simply defined as the difference between the heat of product and the heat of reactant i.e

Enthalphy change = Heat of product – Heat of reactant

ΔH = Hp – Hr

With the above formula, we can easily calculate the enthalphy change as follow

ΔH = Hp – Hr

ΔH = 300 – 800

ΔH = –500KJ.

Therefore, the overall energy change for the reaction between hydrogen and oxygen shown in the diagram above is –500KJ

5 0
3 years ago
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