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3 years ago

a strip of impure copper is given to you. how will you purify it by using chemical effects of electric current ?

2 answers:

6 0

This can be done through electrolysis. Electrolysis is the separation of a substance into two or more substances that may differ from each other and from the original substance by passing an electric current through a solution that contains ions.

In the case of copper, we use a copper (II) sulphate solution which we put in a large beaker. The impure copper will be used as the positive electrode (anode) and for the negative electrode (cathode) will be a bar of pure copper.

When the electric current is switched on, the bar of pure copper which is the cathode increases greatly in size as copper ions leave the anode of impure copper and attach to the cathode. The anode becomes smaller and smaller as it loses copper ions until all that is left of it is impurities in form of a sludge beneath it.

finlep [7]3 years ago

5 0

You would Purify it with magnesium

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Calculate how many grams of sodium azide (NaN3) are needed to inflate a 25.0 × 25.0 × 20.0 cm bag to a pressure of 1.35 atm at a

Luden [163]

Answer : The mass of $NaN_3$ at temperature $20^oC$ 28.47 g.

The mass of $NaN_3$ at temperature $10^oC$ 29.51 g.

Solution : Given,

Pressure of gas = 1.35 atm

Temperature of gas = $20^oC=273+20=293K$ $(0^oC=273K)$

Volume of gas = $25\times 25\times 20cm=12500cm^3=12.5L$ $(1L=1000cm^3)$

Molar mass of $NaN_3$ = 65 g/mole

Part 1 : First we have to calculate the moles of gas at temperature $20^oC$ . The gas produced in the given reaction is $N_2$ .

Using ideal gas equation,

$PV=nRT$

where,

P = pressure of the gas

V = volume of the gas

T = temperature of the gas

n = number of moles of gas

R = Gas constant = 0.0821 Latm/moleK

Now put all the given values in this formula, we get

$(1.35atm)\times (12.5L)=n\times (0.0821Latm/moleK)\times (293K)$

By rearranging the terms, we get the value of 'n'

$n=0.7015moles$

The moles of $N_2$ = 0.7015 moles

The given balanced reaction is,

$20NaN_3(s)+6SiO_2(s)+4KNO_3(s)\rightarrow 32N_2(g)+5Na_4SiO_4(s)+K_4SiO_4(s)$

As, 32 moles of $N_2$ produced from 20 moles of $NaN_3$

So, 0.7015 moles of $N_2$ produced from $\frac{20}{32}\times 0.7015=0.438$ moles of $NaN_3$

Now we have to calculate the mass of $NaN_3$ .

$\text{ Mass of }NaN_3=\text{ Moles of }NaN_3\times \text{ Molar mass of }NaN_3$

$\text{ Mass of }NaN_3=(0.438moles)\times (65g/mole)=28.47g$

Therefore, the mass of $NaN_3$ needed are 28.47 g.

Part 2 : We have to calculate the moles of gas at temperature $10^oC$ and same volume & pressure.

Using ideal gas equation,

$PV=nRT$

Now put all the given values in this formula, we get

$(1.35atm)\times (12.5L)=n\times (0.0821Latm/moleK)\times (283K)$

By rearranging the terms, we get the value of 'n'

$n=0.726moles$

The moles of $N_2$ = 0.726 moles

The given balanced reaction is,

$20NaN_3(s)+6SiO_2(s)+4KNO_3(s)\rightarrow 32N_2(g)+5Na_4SiO_4(s)+K_4SiO_4(s)$

As, 32 moles of $N_2$ produced from 20 moles of $NaN_3$

So, 0.726 moles of $N_2$ produced from $\frac{20}{32}\times 0.726=0.454$ moles of $NaN_3$

Now we have to calculate the mass of $NaN_3$ .

$\text{ Mass of }NaN_3=\text{ Moles of }NaN_3\times \text{ Molar mass of }NaN_3$

$\text{ Mass of }NaN_3=(0.454moles)\times (65g/mole)=29.51g$

Therefore, the mass of $NaN_3$ needed are 29.51 g.

7 0

3 years ago

Na + O2 → Na2O2<br> Can you guys help me !

vfiekz [6]

Answer:

Explanation:

Assuming that you are asking for the full-balanced equations...

2Na + O2 = Na2O2

H2 + O2 = H2O2; This equation is already balanced, there is no need for change.

Please let me know if this is not the answer you are looking for and I will amend the answer.

6 0

3 years ago

Express the sum of 1111 km and 222 km using the correct number of significant digits

kenny6666 [7]

1333 KM is the sum,

6 0

4 years ago

Read 2 more answers

Can carbon atoms share electron with four hydrogen atoms to form a methane molecule? Explain.

Agata [3.3K]

hopefully this helps. if it doesn't then I'm really sorry to say that I wouldn't know.

6 0

3 years ago

Could someone explain this sentence for me ?

Ronch [10]

Answer:

Explanation:

to put this plainly after putting strong electrolytes in water they dissolve to nothing but ions they give you an example and definition of a strong electrolyte I suggest you read those and see if you come up with what I gave you they also tell you that not all strong electrolytes dissolve as strongly as others that are in the example.

4 0

2 years ago