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3 years ago

Which statement is true?

Chemistry

2 answers:

AleksandrR [38]3 years ago

7 0

Exothermic reaction is where there is release of energy during a reaction

The enthalpy of exothermic reaction is negative

The relation between energy of products, reactants and enthalpy of reaction is

Enthalpy of reaction = sum of enthalpy of formation of products - sum of enthalpy of formation of reactants .

As enthalpy of reaction is negative, it means the enthalpy of products is less than the enthalpy of reactants so answer is :

In an exothermic reaction the energy of the product is less than the energy of the reactants.

forsale [732]3 years ago

7 0

An endothermic reaction is a reaction that absorbs heat from the surroundings. That means that the energy of the system must increase. Therefore, the answer must be C as the products should have higher energy than the reactants.

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What is the [OH-],[H3O] and PH for the following

malfutka [58]

The values for hydroxide ions, hydronium ions and pH are found in the attached picture.

Explanation:

See the attached picture.

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brainly.com/question/1525823

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4 0

3 years ago

10.0 g Cu, C Cu = 0.385 J/g°C 10.0 g Al, C Al = 0.903 J/g°C 10.0 g ethanol, Methanol = 2.42 J/g°C 10.0 g H2O, CH2O = 4.18 J/g°C

Mazyrski [523]

Answer:

Lead shows the greatest temperature change upon absorbing 100.0 J of heat.

Explanation:

$Q=mc\Delte T$

Q = Energy gained or lost by the substance

m = mass of the substance

c = specific heat of the substance

ΔT = change in temperature

1) 10.0 g of copper

Q = 100.0 J (positive means that heat is gained)

m = 10.0 g

Specific heat of the copper = c = 0.385 J/g°C

$\Delta T=\frac{Q}{mc}$

$=\frac{100.0 J}{10 g\times 0.385J/g^oC}=25.97^oC$

2) 10.0 g of aluminium

Q = 100.0 J (positive means that heat is gained)

m = 10.0 g

Specific heat of the aluminium= c = 0.903 J/g°C

$\Delta T=\frac{Q}{mc}$

$=\frac{100.0 J}{10 g\times 0.903 J/g^oC}=11.07^oC$

3) 10.0 g of ethanol

Q = 100.0 J (positive means that heat is gained)

m = 10.0 g

Specific heat of the ethanol= c = 2.42 J/g°C

$\Delta T=\frac{Q}{mc}$

$=\frac{100.0 J}{10 g\times 2.42 J/g^oC}=4.13 ^oC$

4) 10.0 g of water

Q = 100.0 J (positive means that heat is gained)

m = 10.0 g

Specific heat of the water = c = 4.18J/g°C

$\Delta T=\frac{Q}{mc}$

$=\frac{100.0 J}{10 g\times 4.18 J/g^oC}=2.39 ^oC$

5) 10.0 g of lead

Q = 100.0 J (positive means that heat is gained)

m = 10.0 g

Specific heat of the lead= c = 0.128 J/g°C

$\Delta T=\frac{Q}{mc}$

$=\frac{100.0 J}{10 g\times 0.128 J/g^oC}=78.125^oC$

Lead shows the greatest temperature change upon absorbing 100.0 J of heat.

3 0

3 years ago

To balance a chemical equation it may be necessary to adjust the

Mars2501 [29]

Answer:

To balance a chemical equation it may be necessary to adjust the coefficients.

Explanation:

The coefficients of a chemical equation are the numbers that you put in front of each reactant and product. They are used to balance the equation and comply with the law of mass conservation.

By adjusting the coefficients you obtain the relative amounts (moles) of each product and reactant, i.e. the mole ratios.

Here an example.

The first information is what is called a word equation. E.g. nitrogen and hydrogen react to form ammonia:

Word equation: hydrogen + nitrogen → ammonia

Skeleton equation: H₂ + N₂ → NH₃

This equation shows the chemical formulae but it is not balanced. The law of mass conservation is not observed.

So, in order to comply with the law of mass conservation you adjust the coefficients as follow.

Balanced chemical equation: 3H₂ + N₂ → 2NH₃

As you see, it was necessary to modify the coefficients. Now the law of conservation of mass is observed and you get the mole ratios:

3 mol H₂ : 1 mol N₂ : 2 mol NH₃

4 0

3 years ago

Which is a substance that could be found in air, water, or soil that is harmful to humans or animals? carbon dioxide fossil fuel

quester [9]

Hi!

The substance that could be found in air, water or soil that is harmful to humans or animals is called pollutant.

Pollutants are the only harmful substances that can be found in these three places. Carbon Dioxide (CO₂) is commonly found in the air, fossil fuels are found in soil and water and smog is found in the air. Only pollutant can be found in these three places as there are varied in its chemical structure. Common pollutants include Sulfur Dioxide (SO₂) which can be found in the air, and Lead, which can be found in water or soil.

Have a nice day!

4 0

3 years ago

Ava threw a hamster at her sister the other day she used 12N of force to accelerate the hamster at 8m/s2.what was the mass of th

xenn [34]

We are given:

The force applied on the poor hamster (F) = 12 N

Acceleration of the poor Hamster (a) = 8 m/s²

Solving for the mass of the Poor Hamster:

From newton's second equation of motion, we know that:

F = ma

replacing the given values

12 = 8 * m

m = 12/8 kg

m = 3/2 kg

The poor Hamster weighs 3/2 kg

8 0

2 years ago