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3 years ago

Sorry if it is blurry

Chemistry

2 answers:

Zina [86]3 years ago

7 0

I really cant read it sorry i tried

Grace [21]3 years ago

4 0

I think its a or c? idk if im wrong sowwie xD

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Can somebody just name all the metalloids, gases, and liquids that are on the periodic table. please this is due in a hour!!!

Lesechka [4]

Answer:

There are six liquid elements present in the periodic table. They are bromine,mercury ,caesium,gallium,rubidium and francium.

The metalloids; boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At) are the elements found along the step like line between metals and non-metals of the periodic table.

The gaseous element group; hydrogen (H), nitogen (N), oxygen (O), fluorine (F), chlorine (Cl) and noble gases helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) are gases at standard temperature and pressure (STP).

Explanation:

7 0

3 years ago

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

Why is the base of an energy pyramid wider than the top

Zepler [3.9K]

It is due to a lack of providable energy to the next trophic level of the energy pyramid. Primary consumers only obtain around 10% of energy that producers have, and the energy depletes as you move further and further up the food chain, until you reach the tertiary consumers which have the least amount of energy at their disposal, meaning there are less of them than other organisms further down the energy pyramid.

Hope this helped!

5 0

3 years ago

Seawater is around a 3% aqueous salt solution.

Eduardwww [97]

Answer:

the answer is distillation

3 0

1 year ago

A 30ml sample of a liquid has a mass of 50 grams. What is the density of the liquid?

mash [69]

Answer:

<h2>Density = 1.67 g/mL</h2>

Explanation:

The density of a substance can be found by using the formula

$Density = \frac{mass}{volume}$

From the question

mass = 50 g

volume = 30 mL

Substitute the values into the above formula and solve for the density

That's

$Density = \frac{50}{30} \\ = \frac{5}{3} \\ = 1.66666...$

Wr have the final answer as

<h3>Density = 1.67 g/mL</h3>

Hope this helps you

5 0

3 years ago