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3 years ago

Enthalpy change depends on the rate at which a substance is heated or cooled true or false

1 answer:

6 0

Enthalpy is a thermodynamic quantity that describes the heat content of a system, that can not be measured directly. That's why we measure change in enthaply, measured in the units joules. The statement that enthalpy change depends on the rate at which a substance is heated or cooled is false. Enthalpy change depends only on the following factors:
-physical state of reactants and products
- quantity of reactants
- allotropic modifications
- temperature and pressure

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Calculate the moles of solute dissolved in 4.2 dm3 of a 0.5 mol / dm3 solution.

Archy [21]

Answer:

Example

0.5 mol of sodium hydroxide is dissolved in 2 dm3 of water. Calculate the concentration of the sodium hydroxide solution formed.

Concentration =

Concentration = 0.25 mol/dm3

Volume units

Volumes used in concentration calculations must be in dm3, not in cm3. It is useful to know that 1 dm3 = 1000 cm3. This means:

divide by 1000 to convert from cm3 to dm3

multiply by 1000 to convert from dm3 to cm3

For example, 250 cm3 is 0.25 dm3 (250 ÷ 1000). It is often easiest to convert from cm3 to dm3 before continuing with a concentration calculation.

Question

100 cm3 of dilute hydrochloric acid contains 0.02 mol of dissolved hydrogen chloride. Calculate the concentration of the acid in mol/dm3.

Reveal answer

Converting between units

The relative formula mass of the solute is used to convert between mol/dm3 and g/dm3:

to convert from mol/dm3 to g/dm3, multiply by the relative formula mass

to convert from g/dm3 to mol/dm3, divide by the relative formula mass

Remember: the molar mass is the Ar or Mr in grams per mol.

Example

Calculate the concentration of 0.1 mol/dm3 sodium hydroxide solution in g/dm3. (Mr of NaOH = 40)

Concentration = 0.1 × 40

= 4 g/dm3

8 0

3 years ago

Thermal energy is the ___ of the kinetic and potential energies of all particles in an object.

galina1969 [7]

Answer:

Explanation:

I forgot butt im surely it is;-)

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3 years ago

When a nitrogen atom becomes an ion, the atom becomes a... A. Negative ion with a radius smaller than the radius of the atom B.

mr Goodwill [35]

Answer:

B. Negative ion with a radius larger than the radius of the atom

Explanation:

When a negative ion is formed, electrons are added to the atom. As electrons are added to the atom, the size of the electron cloud increases accordingly.

As a result of this, a negative ion is always larger than its corresponding atom. Hence, nitrogen ion must be larger than the nitrogen atom based on the facts stated above.

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2 years ago

Early life arose in an oxygen-free environment, but if any of these microbes had somehow come in contact with oxygen, the most l

Leya [2.2K]

Answer:

the effect of oxygen on these types of microbes is it will kill them.

Explanation:

When oxygen present in the environment come in contact with anaerobe bacteria it kill them because oxygen in air act as excited oxygen singlet molecule which will react with the water present in the cell of bacteria and convert it into hydrogen peroxides and bacteria do not have any defense system from hydrogen peroxide and ultimately it kill the bacteria.

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3 years ago

At what point does the radiation start to affect satellites in the atmosphere

Aleksandr-060686 [28]

After that have been up for a while thay are metal

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2 years ago