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3 years ago

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What is the molarity of a solution made by dissolving 21.2 g of sodium hydroxide (NaOH) in enough water to make 7.92 L of soluti

on?
Molar Mass Na: 22.99 g/mol
Molar Mass O: 16.00 g/mol
Molar Mass H: 1.008 g/mol

2 answers:

g100num [7]3 years ago

6 0

M = mol/L so add all molar masses together then divide 21.2g/(molar mass) then divide by Litres

Triss [41]3 years ago

5 0

Hey there!

Attached resolution .

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1) How many molecules are there in 985 mL of nitrogen at 0.0° C and 1.00 x 10-6 mm Hg?

RSB [31]

Answer : The number of molecules present in nitrogen gas are, $3.48\times 10^{13}$

Explanation :

First we have to calculate the moles of nitrogen gas by using ideal gas equation.

$PV=nRT$

where,

P = Pressure of $N_2$ gas = $1.00\times 10^{-6}mmHg=1.32\times 10^{-9}atm$ (1 atm = 760 mmHg)

V = Volume of $N_2$ gas = 985 mL = 0.982 L (1 L = 1000 mL)

n = number of moles $N_2$ = ?

R = Gas constant = $0.0821L.atm/mol.K$

T = Temperature of $N_2$ gas = $0.0^oC=273+0.0=273K$

Now put all the given values in above equation, we get:

$(1.32\times 10^{-9}atm)\times 0.982L=n\times (0.0821L.atm/mol.K)\times 273K$

$n=5.78\times 10^{-11}mol$

Now we have to calculate the number of molecules present in nitrogen gas.

As we know that 1 mole of substance contains $6.022\times 10^{23}$ number of molecules.

As, 1 mole of $N_2$ gas contains $6.022\times 10^{23}$ number of molecules

So, $5.78\times 10^{-11}$ mole of $N_2$ gas contains $(5.78\times 10^{-11})\times (6.022\times 10^{23})=3.48\times 10^{13}$ number of molecules

Therefore, the number of molecules present in nitrogen gas are, $3.48\times 10^{13}$

8 0

3 years ago

Due to the small and highly electronegative nature of fluorine, the oxyacids of the this element are much less common and less s

Molodets [167]

Answer:

HOFO = (0, 0, +1, -1)

Explanation:

The formal charge (FC) can be calculated using the following equation:

$FC = V - N - \frac{1}{2}B$

<u>Where:</u>

V: are the valence electrons

N: are the nonbonding electrons

B: are the bonding electrons

The arrange of the atoms in the oxyacid is:

H - O₁ - F - O₂

Hence, the formal charge (FC) on each of the atoms is:

H: FC = 1 - 0 - 1/2*(2) = 0

O₁: FC = 6 - 4 - 1/2*(4) = 0

F: FC = 7 - 4 - 1/2*(4) = +1

O₂: FC = 6 - 6 - 1/2*(2) = -1

We can see that the negative charge is in the oxygen instead of the most electronegative element, which is the F. This oxyacid is atypical.

I hope it helps you!

3 0

3 years ago

Biuret reagent will indicate the presence of

weeeeeb [17]

Biuret reagent will indicate the presence of protein in a given sample. It is also known as the Piotrowski's test. This reagent consists of copper (II) sulfate and sodium hydroxide. It detects peptide bonds by the reaction of the copper ions in an alkaline solution. The copper ions would form violet colored complexes when peptide is present in the solution. From this test, concentration can be calculated since the intensity of the color depends on the amount of peptide bonds and according to the Beer-Lambert law concentration and the absorption of light is proportional. The concentration is calculated by a spectrophotometric technique at a wavelength of 540 nm.

5 0

3 years ago

The bigger the magnitude , the bigger the Earthquake

aleksley [76]

Answer:

True, in as far as greater magnitude = greater power.

7 0

3 years ago

Read 2 more answers

Given the reaction: A + B <--> C + D

Lady_Fox [76]

Answer:

A.) 4.0

Explanation:

The general equilibrium expression looks like this:

$K = \frac{[C]^{c} [D]^{d} }{[A]^{a} [B]^{b} }$

In this expression,

-----> K = equilibrium constant

-----> uppercase letters = molarity

-----> lowercase letters = balanced equation coefficients

In this case, the molarity's do not need to be raised to any numbers because the coefficients in the balanced equation are all 1. You can find the constant by plugging the given molarities into the equation and simplifying.

$K = \frac{[C]^{c} [D]^{d} }{[A]^{a} [B]^{b} }$ <----- Equilibrium expression

$K = \frac{[2 M] [2 M]}{[1 M] [1 M] }$ <----- Insert molarities

$K = \frac{4}{1 }$ <----- Multiply

$K = 4$ <----- Divide

6 0

2 years ago