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3 years ago

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

Chemistry

1 answer:

Archy [21]3 years ago

8 0

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

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Read 2 more answers

Which solution contains the smallest number of moles of sucrose (c12h22o11, molar mass = 342.30 g/mol)? 2,000 ml of a 5.0 × 10–5

Iteru [2.4K]

> 2,000 mL of a 5.0 × 10–5% (w/v) sucrose solution

5.0 × 10–3 g/mL * 2000 mL * (1 mol / 342.30 g) = 0.0292 mol

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Answer:

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3 years ago

What is the relationship between atmospheric pressure and the density of gas particles in an area of increasing pressure? As air

Marina86 [1]

We need to know the relationship between atmospheric pressure and the density of gas particles in an area of increasing pressure.

The relationship is: As air pressure in an area increases, the density of the gas particles in that area increases.

For any gaseous substance, density of gas is directly proportional to pressure of gas.

This can be explained from idial gas edquation:

PV=nRT

PV= $\frac{w}{M}$ RT [where, w= mass of substance, M=molar mass of substance]

PM= $\frac{w}{V}$ RT

PM=dRT [where, d=density of thesubstance]

So, for a particular gaseous substance (whose molar mass is known), at particular temperature, pressure is directly related to density of gaseous substance.

Therefore, as air pressure in an area increases, the density of the gas particles in that area increases.

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3 years ago