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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

You might be interested in

For the vaporization reaction Br2(l) → Br2(

oksian1 [2.3K]

The temperature at which the process be spontaneous is calculated as follows

delta G = delta H -T delta S

let delta G be =0

therefore delta H- T delta s =0

therefore T= delta H/ delta S
convert 31 Kj to J = 31 x1000= 31000 j/mol

T=31000j/mol /93 j/mol.k =333.33K

3 0

3 years ago

Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an el

givi [52]

Answer: The amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

Explanation:

We are given:

Moles of electron = 1 mole

According to mole concept:

1 mole of an atom contains $6.022\times 10^{23}$ number of particles.

We know that:

Charge on 1 electron = $1.6\times 10^{-19}C$

Charge on 1 mole of electrons = $1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C$

$Cu^{2+}+2e^-\rightarrow Cu$

$2\times 96500=193000C$ is passed to deposit = 1 mole of copper

63.5 g of copper is deposited by = 193000 C

$14\times 1000g=14000g$ of copper is deposited by = $\frac{193000}{63.5}\times 14000=42551181 C$

To calculate the time required, we use the equation:

$I=\frac{q}{t}$

where,

I = current passed = 40.0 A

q = total charge = 42551181 C

t = time required = ?

Putting values in above equation, we get:

$40.0=\frac{42551181 C}{t}\\\\t=1063779sec$

Converting this into hours, we use the conversion factor:

1 hr = 3600 seconds

So, $1063779s\times \frac{1hr}{3600s}=295hr$

Hence, the amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

3 0

3 years ago

If an ideal gas has a pressure of 2.97 atm, a temperature of 449 K, and has a volume of 58.35 L, how many miles of gas are in th

soldi70 [24.7K]

N = ?

T = 449 K

V = 58.35 L

P =2.97

R = 0.082

Use the clapeyron equation:

P x V = n x R x T

2.97 x 58.35 = n x 0.082 x 449

173.2995 = n x 36.818

n = 173.2995 / 36.818

n = 4.70 moles

hope this helps!

7 0

3 years ago

Someone thought there was water in Beaker C. He drank some and quickly spat out.He said that it was salty. Explain why this happ

fomenos

Answer:

He assumed wrongly

Explanation:

It happened this way because the person assumed wrongly.

Most other compounds have the same physical appearance as water especially when in liquid form.

This can be a very tricky one in the laboratory.
The sense of taste is not the best way to fathom what a particular compound is made up of.
This is the reason why this student or person faced this sort of problem.
Water has different properties that can be tested for using simple techniques in the laboratory.

4 0

3 years ago

Tell why someone should visit this planet neptune, what they might be able to see or do, what they will

leonid [27]

362782bebehhehdhduwkekennebsbdhr

7 0

3 years ago