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Schach [20]
3 years ago
12

URGENT ! PLEASE ANSWER QUICKLY

Chemistry
2 answers:
Bumek [7]3 years ago
7 0

Answer:If we dissolve NaF in water, we get the following equilibrium:

text{F}^-(aq)+text{H}_2text{O}(l) rightleftarrows text{HF}(aq)+text{OH}^-(aq)

The pH of the resulting solution can be determined if the  K_b of the fluoride ion is known.

20.0 g of sodium fluoride is dissolve in enough water to make 500.0 mL of solution. Calculate the pH of the solution. The  K_b of the fluoride ion is 1.4 × 10 −11 .

Step 1: List the known values and plan the problem.

Known

mass NaF = 20.0 g

molar mass NaF = 41.99 g/mol

volume solution = 0.500 L

K_b of F – = 1.4 × 10 −11

Unknown

pH of solution = ?

The molarity of the F − solution can be calculated from the mass, molar mass, and solution volume. Since NaF completely dissociates, the molarity of the NaF is equal to the molarity of the F − ion. An ICE Table (below) can be used to calculate the concentration of OH − produced and then the pH of the solution.

Explanation:

marysya [2.9K]3 years ago
4 0

Answer:

not sure if this is 100% correct but this is what i got first question: molarity=mol/L 5g*1mol/58.44g=5/58.44 =0.085558mol 4.8m=0.085558/L L=0.0178

jiujuan avatar

second question: pH = - log [H3O+] pH= -log [4.6*10^-9] = 8.33724216

Explanation:

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A metal M forms the oxide M2O. When 0.890 grams of M reacts with pure oxygen, 0.956 grams of M2O form. Write the balanced equati
Alla [95]

The molar mass of M is  0.225g/mol and the element M is Hydrogen

If a metal M combines with an oxygen element to form the oxide, M_2O then the chemical reaction will be expressed as:

4M + O_2 -> 2M_2O\\

This shows that 4 moles of an unknown element M react with the oxygen element to produce the oxide M_2O

Given the following parameters

Mass of M = 0.890 grams

Mass of M_2O = 0.956 grams

Get the molar mass of M:

Molar mass = Mass/number of moles

Molar mass = 0.890/4

Molar mass = 0.225g/mol

Hence the molar mass of M is  0.225g/mol and the element M is Hydrogen

Learn more here: brainly.com/question/6996520

5 0
2 years ago
Read 2 more answers
Human blood has a pH between 7.35 and 7.45. Which of the following best describes human blood?
uysha [10]

Answer:

C. slightly basic

Explanation:

0-7 = acidic

7 = neutral

7-14 = basic

- Since the pH is just over 7, the answer would be slightly basic.

- Hope this helps! Please let me know if you need a further explanation.

6 0
3 years ago
A sodium atom and sodium ion have the same
Ilia_Sergeevich [38]

<u>Answer:</u>

a) number of neutrons

<u>Explanation:</u>

A sodium ion is formed when an electron is removed from a sodium atom. This means that the atom's number of electrons changes, but the number of neutrons remains unchanged.

However, as the number of electrons changes, the electric charge and the electronic structure change, which means that a sodium atom and a sodium ion do not have the same number of electrons, nor do they have the same electric charge or electronic structure.

Therefore, option a) is the correct option.

3 0
1 year ago
What source provides most of the energy consumed in the United States?
umka2103 [35]

Answer:

Fossil fuels

Explanation:

Fossil fuels — natural gas, coal, and petroleum, and — provide most (63 %) of the energy consumed in the United States

The breakdown in 2019 was  

Natural gas 38 %

Coal             24 %

Petroleum      1 %

4 0
3 years ago
Binary compound of oxygen and an unknown element,X, has the formula XO2 and is 69.55 mass % oxygen, what is the weight of elemen
marissa [1.9K]

Answer:

Weight of element X = 14.01 gram

Explanation:

Mass percentage is calculated by using :

Percent =\frac{Mass\ of\ element}{Total\ mass}\times 100

O\ Percent=\frac{Mass\ of\ O}{Total\ mass\ of\ XO2}\times 100

Mass of O = 16.0 gram

let mass of X = X grams = ?

Mass of XO2 = mass of X + 2(mass of O)

Mass of XO2 = X + 2(16)

Mass of XO2 = X + 32

Total mass of O in the compound = 2(16) = 32 grams

Percent O = 69.55 %

Percent\ O =\frac{Mass\ of\ O}{Total\ mass\ of\ XO2}\times 100

69.55=\frac{32}{X+32}\times 100

\frac{69.55}{100}=\frac{32}{X+32}

0.6955=\frac{32}{X+32}

0.6955\times (X+32)=32

0.6955X+ 22.256=32

0.6955X=9.744

X=\frac{9.744}{0.6955}

X =14.01

weight of element X = 14.01 gram

14.01 is mass of nitrogen N

The correct formula of this element is NO2

6 0
3 years ago
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