What causes your skin to feel warm when it is in the sun on a summer day?

For Na2HPO4:(( (Note that for H3PO4, ka1= 6.9x10-3, ka2 = 6.4x10-8, ka3 = 4.8x10-13 ) a) The active anion is H2PO4- b) The activ

Komok [63]

Answer:

Check the explanation

Explanation:

Answer – Given, $H_3PO_4$ acid and there are three Ka values

$K_{a1}=6.9x10^8, K_{a2} = 6.2X10^8, and K_{a3}=4.8X10^{13}$

The transformation of $H_2PO_4- (aq) to HPO_4^2-(aq)$ is the second dissociation, so we need to use the Ka2 = 6.2x10-8 in the Henderson-Hasselbalch equation.

Mass of KH2PO4 = 22.0 g , mass of Na2HPO4 = 32.0 g , volume = 1.00 L

First we need to calculate moles of each

Moles of KH2PO4 = 22.0 g / 136.08 g.mol-1

= 0.162 moles

Moles of Na2HPO4 = 32.0 g /141.96 g.mol-1

= 0.225 moles

[H2PO4-] = 0.162 moles / 1.00 L = 0.162 M

[HPO42-] = 0.225 moles / 1.00 L = 0.225 M

Now we need to calculate the pKa2

pKa2 = -log Ka

= -log 6.2x10-8

= 7.21

We know Henderson-Hasselbalch equation

pH = pKa + log [conjugate base] / [acid]

pH = 7.21 + log 0.225 / 0.162

= 7.35

The pH of a buffer solution obtained by dissolving 22.0 g of KH2PO4 and 32.0 g of Na2HPO4 in water and then diluting to 1.00 L is 7.35

6 0

3 years ago

Sierra has a special kind of liquid rubber. She knows that ultraviolet light is

lana66690 [7]

Answer:

See explanation

Explanation:

Light is a form of energy. Both ultraviolet light and xrays are part of the electromagnetic spectrum.

As was said in the question, ultraviolet rays is absorbed by the rubber. We must know that prolonged exposure of this piece of rubber to incident ultraviolet light causes the vaporization of volatile materials in the rubber.

When volatile materials in the rubber vaporize, the rubber can become solid. Thus, ultraviolet light can cause rubber to become solid.

However, not all types of light can do this hence it does matter the type of light that falls on the rubber material.

8 0

3 years ago

What is the condensed structural formula of the product of the reaction of 2,7-dimethyl-4-octene with hydrogen and a metal catal

gavmur [86]

The condensed structural formula of the product of the reaction of 2,7-dimethyl-4-octene with hydrogen and metal catalyst.

Ch3 CH(CH3) CH2 CH2 CH2 CH2 CH(CH3) CH3

Equation is as follows

CH3 CH(CH3) CH2 C=C CH2 CH(CH3) CH3 + H2→

CH3 CH(CH3)CH2 CH2 CH2 CH2 CH(CH3) CH3

metal catalyst example is nickel and the name of structure formed is
2,7- dimethyl octane

6 0

3 years ago

When a person pushes off a wall with 15N of force,how much force does the wall push back

aivan3 [116]

Newton's third law of motion states that for every action force, there is an equal and opposite reaction force so that means that the wall is pushing you with the same amount of force that you put on it.

5 0

3 years ago

A monomer is added to the end of a polymer chain in a __________ reaction.

aalyn [17]

Dehydration reaction

6 0

3 years ago

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