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2 years ago

Water is unique because

Chemistry

1 answer:

wolverine [178]2 years ago

7 0

Answer:

b. It exists in three different states at normal conditions in the Earth's atmosphere

Explanation:=

Snow, rain and water vapour can exist at normal conditions in the Earth's atmosphere.

a. is wrong. Only hydrogen and helium can escape Earth's atmosphere in significant amounts.

c. is wrong. The molecules of every substance are in motion even when it is solid.

d. is wrong. Other substances can form from a wide range of chemical processes.

e. is wrong. All substances expand when they become a gas.

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Balance the equation for <br> __Ca+__Pb(NO3)2—__Pb+__Ca(NO3)2

svp [43]

Answer:

Ca + Pb(NO3)2 → Pb + Ca(NO3)2

Explanation:

This is an oxidation-reduction (redox) reaction:

PbII + 2 e- → Pb0

(reduction)

Ca0 - 2 e- → CaII

(oxidation)

Pb(NO3)2 is an oxidizing agent, Ca is a reducing agent.

5 0

2 years ago

Which of the following is not produced in

Anastaziya [24]

1. greenhouse gases. these are not formed because nuclear fission involves the modification of atoms. It does not give rise to other molecules.

3 0

3 years ago

Read 2 more answers

You decided to prepare a phosphate buffer from solid sodium dihydrogen phosphate (NaH2PO4) and disodium hydrogen phosphate (Na2H

KIM [24]

Answer:

For disodium hydrogen phosphate:

5.32g Na2HPO4

For sodium dihydrogen phosphate:

7.65g Na2HPO4

Explanation:

First, you have to put all the data from the problem that you going to use:

-NaH2PO4 (weak acid)

-Na2HPO4 (a weak base)

-Volume = 1L

-Buffer pH = 7.00

-Concentration of [NaH2PO4 + Na2HPO4] = 0.100 M

What we need to find the pKa of the weak acid, in this case NaH2PO4, for that you need to find the Ka (acid constant) of NaH2PO4, and for this we use the pKa of the phosphoric acid as follow:

H3PO4 = H2PO4 + H+ pKa1 = 2.14

H2PO4 = HPO4 + H+ pKa2 = 6.86

HPO4 = PO4 + H+ pKa3 = 12.4

So, for the preparation of buffer, you need to use the pKa that is near to the value of the pH that you want, so the choice will be:

pKa2= 6.86

Now we going to use the Henderson Hasselbalch equation for the pH of a buffer solution:

pH = pKa2 + log [(NaH2PO4)/(Na2HPO4)]

The solution of the problem is attached to this answer.

Download odt

7 0

3 years ago

Predict the products of the reaction below

Mrrafil [7]

Answer:

HNO₃ + NaOH ---> NaNO₃ + H₂O

Explanation:

This reaction appears to be a double-displacement reaction. In these reaction, the cation of one compound is swapped with the cation of another.

As such, the hydrogen cation (H⁺) from HNO₃ is swapped with the sodium cation (Na⁺) of NaOH.

Luckily, all of the cations have a +1 charge and the anions have a -1 charge. This means that no coefficients are necessary to balance the reaction.

The <u>complete balanced </u>equation is:

HNO₃ + NaOH ---> NaNO₃ + H₂O

4 0

1 year ago

Identify some other substances (besides KCl) that might give a positive test for chloride upon addition of AgNO3. do you think i

nlexa [21]

Answer:

-The other substances that give a positive test with AgNO3 are other chlorides present, iodides and bromide.

-It is reasonable to exclude iodides and bromides but it is not reasonable to exclude other chlorides

Explanation:

In the qualitative determination of halogen ions, silver nitrate solution(AgNO3) is usually used. Now, various halide ions will give various colours of precipitate when mixed with with silver nitrate. For example, chlorides(Cl-) normally yield a white precipitate, bromides(Br-) normally yield a cream precipitate while iodides (I-) normally yield a yellow precipitate. Thus, all these ions or some of them may be present in the system.

With that being said, if other chlorides are present, they will also yield a white precipitate just like KCl leading to a false positive test for KCl. However, since other halogen ions yield precipitates of different colours, they don't lead to a false test for KCl. Thus, we can exclude other halides from the tendency to give us a false positive test for KCl but not other chlorides.

5 0

3 years ago