Which process will change a substance chemically? A. boiling B. melting C. burning D. evaporating

What is the oxidation state of Hg in Hg2Cl2?

Anna [14]

Answer:

+1

Explanation:

Electrochemistry. In oxidation–reduction (redox) reactions, electrons are transferred from one A redox reaction is balanced when the number of electrons lost by the reductant Hg(l)∣Hg2Cl2(s)∣Cl−(aq) ∥ Cd2+(aq)∣Cd(s).

As is evident from the Stock number, mercury has an oxidation state of +1. This makes sense, as chlorine usually has an oxidation state of -1.

5 0

3 years ago

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.8

Lubov Fominskaja [6]

Complete Question

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.82 when exactly 13 mL of base had been added, you notice that the concentration of the unknown acid was 0.1 M. What is the pKa of your unknown acid?

Answer:

The pK_a value is $pK_a =7.82$

Explanation:

From the question we are told

The volume of base is $V_B = 26.mL = 0.0260L$

The pH of solution is $pH = 7.82$

The concentration of the acid is $C_A = 0.1M$

From the pH we can see that the titration is between a strong base and a weak acid

Let assume that the the volume of acid is $V_A = 18mL= 0.018L$

Generally the concentration of base

$C_B = \frac{C_AV_A}{C_B}$

Substituting value

$C_B = \frac{0.1 * 0.01800}{0.0260}$

$C_B= 0.0692M$

When 13mL of the base is added a buffer is formed

The chemical equation of the reaction is

$HA_{(aq)} + OH^-_{(aq)} --------> A^{+}_{(aq)} + H_2 O_{(l)}$

Now before the reaction the number of mole of base is

$No \ of \ moles[N_B] = C_B * V_B$

Substituting value

$N_B = 0.01300 * 0.0692$

$= 0.0009 \ moles$

Now before the reaction the number of mole of acid is

$No \ of \ moles = C_B * V_B$

Substituting value

$N_A = 0.01800 *0.1$

$= 0.001800 \ moles$

Now after the reaction the number of moles of base is zero i.e has been used up

this mathematically represented as

$N_B ' = N_B - N_B = 0$

The number of moles of acid is

$N_A ' = N_A - N_B$

$= 0.0009\ moles$

The pH of this reaction can be mathematically represented as

$pH = pK_a + log \frac{[base]}{[acid]}$

Substituting values

$7.82 = pK_a +log \frac{0.0009}{0.0009}$

$pK_a =7.82$

8 0

3 years ago

5. The density of ethanol is 0.789 g/mL. Find the mass of a sample of ethanol that has a volume of 150.0 mL.

GenaCL600 [577]

. 00526 g is mass of ethanol

6 0

3 years ago

ANSWER FAST PLZZZ!!!!!!!!!!!!!

Anestetic [448]

Answer: D. test tubes, thermometers, etc

I think this is the correct answer. Sorry if it is not.

Explanation:

6 0

3 years ago

What happens to the electronegativity as you go from Lithium to Francium?<br> Why?

Y_Kistochka [10]

Answer:

Electronegativity in group 1 decreases as we go from Lithium to Francium.

Explanation:

Electronegativity is defined as the tendency of an element to attract an electron pair towards itself.

In a group generally this tendency decreases from top to bottom as the size of the atom increases and hence the positive nucleus get far from the outer orbital.

In the same way group 1 elements i.e. from Lithium to Francium electronegativity decreases.

8 0

3 years ago