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3 years ago

In what method Copper sulphate solution change blue to colourless ??

1 answer:

7 0

Answer: When an iron nail immersed in the solution of copper sulphate than iron displaces copper from the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.

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How many grams of sodium fluoride should be added to 300. mL of 0.0310 M of hydrofluoric acid to produce a buffer solution with

Kisachek [45]

Answer : The mass of sodium fluoride added should be 0.105 grams.

Explanation : Given,

The dissociation constant for HF = $K_a=6.8\times 10^{-4}$

Concentration of HF (weak acid)= 0.0310 M

First we have to calculate the value of $pK_a$ .

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (6.8\times 10^{-4})$

$pK_a=4-\log (6.8)$

$pK_a=3.17$

Now we have to calculate the concentration of NaF.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[NaF]}{[HF]}$

Now put all the given values in this expression, we get:

$2.60=3.17+\log (\frac{[NaF]}{0.0310})$

$[NaF]=0.00834M$

Now we have to calculate the moles of NaF.

$\text{Moles of NaF}=\text{Concentration of NaF}\times \text{Volume of solution}=0.00834M\times 0.300L=0.0025mole$

Now we have to calculate the mass of NaF.

$\text{Mass of }NaF=\text{Moles of }NaF\times \text{Molar mass of }NaF=0.0025mole\times 42g/mole=0.105g$

Therefore, the mass of sodium fluoride added should be 0.105 grams.

4 0

4 years ago

Use the molar bond enthalpy data in the table to estimate the value of Δ∘rxn

MakcuM [25]

Answer:

ΔH°rxn = - 433.1 KJ/mol

Explanation:

CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g)

⇒ ΔH°rxn = 4ΔH°HCl(g) + ΔH°CCl4(g) - 4ΔH°Cl2(g) - ΔH°CH4(g)

∴ ΔH°Cl2(g) = 0 KJ/mol.....pure element in its reference state

∴ ΔH°CCl4(g) = - 138.7 KJ/mol

∴ ΔH°HCl(g) = - 92.3 KJ/mol

∴ ΔH°CH4(g) = - 74.8 KJ/mol

⇒ ΔH°rxn = 4(- 92.3 KJ/mol) + (- 138.7 KJ/mol) - 4(0 KJ/mol) - (- 74.8 KJ/mol)

⇒ ΔH°rxn = - 369.2 KJ/mol - 138.7 KJ/mol - 0 KJ/mol + 74.8 KJ/mol

⇒ ΔH°rxn = - 433.1 KJ/mol

4 0

3 years ago

Read 2 more answers

Which statement correctly compares sound and earthquake waves?

kakasveta [241]

Can you give me the statements please?

6 0

3 years ago

Read 2 more answers

What is the correct name for Au3N?

Reptile [31]

Answer:

option D= Gold (I) nitride

Explanation:

The name of the given compound is gold(I) nitride.

Molar mass can be determine by following way:

molar mass Au3N = (molar mass of gold × 3) + (molar mass of nitrogen)

molar mass Au3N = (196.97 × 3 ) + ( 14 )

molar mass of Au3N = 590.91 g/mol + 14 g/mol

molar mass of Au3N = 604.91 g/mol

The nitrogen has valency of -3 so three Au(+1) will require while the valency of Au is (1+) one nitrogen will require to make the compound overall neutral.

Au3N

3(1+) + (-3) = 0

+3 - 3 = 0

0 = 0

The overall charge is 0, the compound will be neutral.

8 0

3 years ago

The bond formed between two nonmetal atoms is called covalent. this typw of bond arises from

gavmur [86]

This is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions

6 0

3 years ago

In what method Copper sulphate solution change blue to colourless ??​

In what method Copper sulphate solution change blue to colourless ??