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3 years ago

Which of the following is a chemical change?

2 answers:

3 0

Hi I'm in Chemistry too this year,
I believe D is correct because usually physical changes are things like density, color or quantity.

NNADVOKAT [17]3 years ago

3 0

D splitting water into hydrogen and oxygen yes because there is a chemical reaction with the molecules that changes the water

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In a pendulum, a continuous change occurs between kinetic energy and

Masja [62]

It should be potential energy!!!

7 0

3 years ago

What elements react the most? Like have the most reactivity.

Vera_Pavlovna [14]

If you mean what group of elements react the most, the answer is the alkali metals and the halogens because they both only either need to gain or lose one electron. If you mean the most reactive element, it would be fluorine because it has the most electronegativity.

4 0

3 years ago

Select the compounds from the list below which are insoluble in water

natulia [17]

Answer:

Insoluble in water:

BaSO4

PbCl2

Cu2O

AgBr

Explanation:

Water turns out to be a good solvent for ionic substances, or in general, polarized covalent substances. On the other hand, it is not a good solvent for non-polar substances, these being the vast majority of covalent substances.

5 0

3 years ago

The rules of engagement (roe) working group is often used to _____. (select all that apply.)

Gnesinka [82]

Answer:

proactively develop ROE as well as responding to requests for additional ROE measures

Explanation:

The rules of engagement (roe) working group is a group who's main job is to proactively develop ROE as well as responding to requests for additional ROE measures. Rules of Engagement are a set or rules or directives for military soldiers that define the circumstances, conditions, degree, and manner in which the use of force can be used.

3 0

4 years ago

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