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3 years ago

How many Na ions are in 2.7 g of NaCl? Answer in units of ions.

Chemistry

1 answer:

Viefleur [7K]3 years ago

3 0

Answer:

$2.778 * 10^{22}$

Explanation:

Weight of NaCl is equal to sum of weight of one mole of sodium and one mole of chloride.

Mathematically, it can be represented as -

1 mol (Na) $+$ 1 mol (Cl) $= 23.0 + 35.5 = 58.5$ g/mol

In $58.5$ gram of NaCl, there is one mole of Na or $6.02 * 10^{23}$ ions

In one gram of NaCl, there will be

$\frac{6.02 * 10^{23}}{58.5}$ sodium ions

In $2.7$ grams of NaCl, the number of sodium ions will be -

$\frac{6.02 * 10^{23}}{58.5} * 2.7$

$2.778 * 10^{22}$

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Answer:

Explanation:

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3 years ago

1- Alum used in cooking is potassium aluminum sulfate hydrate, KAl(SO4)2. XH2O. To find the value of X, you can heat the sample

Burka [1]

Answer:

THE VALUE OF X IS 7 AND THE FORMULA OF THE HYDRATED SALT IS KAl(SO4)2.7H20

Explanation:

1. write out the varibales given in thequestion:

Mass of the hydrated salt = 4.74 g

Mass of water lost = 2.16 g

Formula of the hydrated salt = KAl(SO4)2. XH20

2. calculate the molar mass of the salt and that of water of crystallization:

Molar mass of anhydrous salt = ( K = 39, Al = 27, S = 32, 0=16)

= ( 39 + 27 + 32*2 + 16 * 8

= (39 + 27 + 64 + 128)

= 258 g/mol

Molar mass of water = 18 g/mol

3. Use this expression to calculate X:

The expression,

XH20 / molar mass of anhydrous salt = Mass of water lost / Mass of hydrated salt.

X = molar mass of anhydrous salt * mass of water lost / mass of anhydrous salt * H20

where XH20 is the molar mass of water of crystallization, is used to calculate the value of X.

4. Solve for X:

So therefore:

X = 258 * 2.16 / 4.74 * 18

X = 557.28/ 85.32

X = 6.53

X is approximately 7.

The value of X is 7 and the formula pf the hydrated salt is KAl(SO4)2.7H20

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3 years ago

A student performs an experiment to find the percentage of water in a hydrate. He determines that the hydrate contains 22% water

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Answer:

A feasible error could have been the removal of the sample before all water evaporated.

Explanation:

In order to determine the percentage of water in an hydrate, an experiment that could be performed is the heating of the sample until the mass does not change. If the student heated the sample an insufficient amount of time, water will be present in the sample, thus reducing the percentage reported.

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3 years ago

At a given temperature the vapor pressure of pure liquid benzene and toluene are 745 torr and 290 torr, respectively. A solution

IRISSAK [1]

Answer:

Vapour pressure of benzene over the solution is 253 torr

Explanation:

According to Raoult's law for a mixture of two liquid component A and B-

vapour pressure of a component (A) in solution = $x_{A}\times P_{A}^{0}$

vapour pressure of a component (B) in solution = $x_{B}\times P_{B}^{0}$

Where $x_{A},x_{B}$ are mole fraction of component A and B in solution respectively

$P_{A}^{0},P_{B}^{0}$ are vapour pressure of pure A and pure B respectively

Here mole fraction of benzene in solution is 0.340 and vapour pressure of pure benzene is 745 torr

So, vapour pressure of benzene in solution = $0.340\times 745 torr$

= 253 torr

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3 years ago

If you want to use a serial dilution to make a 1/50 dilution. The first dilution you make is a 1/5 dilution with a total volume

fomenos

Answer:

Explanation:

A serial dilution is a dilution that is made fractionated. The stock solution is diluted, then this now solution is diluted, and then successively. The final dilution is the multiplication of the steps dilutions.

The representation of the dilution is v/v (volume per volume) indicates how much of the stock solution is in the total volume of the solution. So 1/5 indicates 1 mL to 5 mL of the solution. If the final volume must be 1 mL, then the stock solution must be 0.2 mL (0.2/1 = 1/5), and the volume of the solvent is 1 mL - 0.2 = 0.8 mL.

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3 years ago