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3 years ago

Calculate the amount of nacl needed to prepare 50 ml of 0.9% nacl solution and 20% nacl solution

1 answer:

6 0

Your answer would be,
Formula: Molarity (M) = Number of moles of solute/Solutions volume Liters

0.009(50) = .45 gm dissolved in 50 ml H2o
= 0.20(50) = 10 gm

Hope that helps!!!

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Answer the following questions in brief.<br>Why does silver get tarnished on exposure to air?

Studentka2010 [4]

Answer: When silver is exposed to sulfur-containing gases in the air, it discolours and then darkens as it reacts with the gas to form a surface layer of tarnish. This process is called tarnishing.

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3 years ago

Select all of the statements about fatty acid melting points that are true.

Sindrei [870]

The answers that apply include;

A saturated fatty acid with a greater molar mass has a higher melting point than a saturated fatty acid with a low molar mass
A saturated fatty acid has a higher melting point than an unsaturated fatty acid

Saturated acids do not have double bonds in their hydrocarbon tails. Therefore, because there are no kinks in the chains, the chains are well compacted due to numerous hydrogen bonds between each. The larger the chains (directly proportional to molar mass), the higher the melting point of these fats.

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4 years ago

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Ira Lisetskai [31]

The answer is D! This is because there is a change the colour, a change in odor and a precipitate formed!

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3 years ago

What is the % mass of a solution composed of 265mg of glucose dissolved in 3 grams of water?

Zarrin [17]

Answer:

8.1%

Explanation:

<h3><u><em>mass of glucose/ total mass of solution x 100</em></u></h3>

So first 265mg into grams = 0.265 g

0.265 + 3 = 3.265

mass of glucose= 0.265

total mass of solution= 3.265

0.265/3.265 x 100 = 8.1% (rounded to 2 s.f)

7 0

4 years ago

How many water molecules are found within the crystalline structure of one hydrate molecule?

den301095 [7]

a. The Mass of water driven off = 0.15 g

b. Moles of anhydrate = 0.00257 moles

c. Moles of water driven off is 0.00833 moles

d. There are 3 moles of water within the crystalline structure of one molecule of the hydrated salt.

e. The molecular formula of the hydrated salt will be X.3H₂O

<h3>What is the mass of water driven off from the hydrated salt?</h3>

a. The mass of water driven off from the hydrated salt is:

Mass of water driven off = 0.5 g - 0.35 g

Mass of water driven off = 0.15 g

b. Molecular mass of salt = 136 g/mol

moles of anhydrate = 0.35/136

Moles of anhydrate = 0.00257 moles

c. Moles of water driven off = mass/molar mass

molar mass of water = 18 g/mol

Moles of water driven off = 0.15/18

Moles of water driven off = 0.00833 moles

d. Moles of water within the crystalline structure of one molecule of the hydrated salt is determined by converting to whole number mole ratio by dividing with the smallest ratio,

Salt to water ratio = 0.00257 /0.00257 : 0.00833/0.00257

Salt to water ratio = 1 : 3

Therefore, there are 3 moles of water within the crystalline structure of one molecule of the hydrated salt.

e. Assuming the anhydrous salt is X, the molecular formula of the hydrated salt will be X.3H₂O

Learn more about hydrated salts at: brainly.com/question/14447094

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2 years ago