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2 years ago

How many electrons are in the outermost energy level of oxygen who's atomic number is 8?

Chemistry

1 answer:

andrey2020 [161]2 years ago

8 0

There are two in the first ring leaving only six out of eight to go on the next

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What is the term for an object's strength of motion?

Andrei [34K]

I'm pretty sure its momentum

3 0

3 years ago

Calculate the ph of a solution formed by mixing 200.0 ml of 0.30 m hclo with 300.0 ml of 0.20 m kclo. the ka for hclo is 2.9 × 1

velikii [3]

C(HClO) = 0,3 M.
V(HClO) = 200 mL = 0,2 L.
n(HClO) = c(HClO) · V(HClO).
n(HClO) = 0,06 mol.
c(KClO) = 0,2 M.
V(KClO) = 0,3 L.
n(KClO) = 0,06 mol.
V(buffer solution) = 0,2 L + 0,3 L = 0,5 L.
ck(HClO) = 0,06 mol ÷ 0,5 L = 0,12 M.
cs(KClO) = 0,06 mol ÷ 0,5 L = 0,12 M.
Ka(HClO) = 2,9·10⁻⁸.
This is buffer solution, so use Henderson–Hasselbalch equation:
pH = pKa + log(cs ÷ ck).
pH = -log(2,9·10⁻⁸) + log(0,12 M ÷ 0,12 M).
pH = 7,54 + 0.
pH = 7,54

6 0

3 years ago

A 1.87 L aqueous solution of KOH contains 155 g of KOH . The solution has a density of 1.29 g/mL . Calculate the molarity ( M ),

Semenov [28]

Answer:

[KOH] : 1.47 M

[KOH] : 1.22 m

[KOH]: 6.42 % mass percent.

Explanation:

First of all we must determine the volume of solution. We have to work with the density

Density = mass / volume

1.29 g/ml = mass / 1870 ml

1.29 g/ml . 1870 ml = 2412.3

Now we must convert the mass to moles

155g / 56.1 g/ mol = 2.76 moles

Now we can calculate molarity

2.76 mol / 1.87 L = 1.47 M

To calculate molality we have to find out the mass of solvent

mass solute + mass solvent = mass solution

155 g + mass solvent = 2412.3 g

2412.3g - 155g = 2257.3g

We have to convert the 2257.3 g to kg

2257.3 g = 2.25 kg

molality = 2.76 moles / 2.25 kg = 1.22 m

To find out the % mass percentation, we have to calculate the mass of solute in 100 g of solution.

In 2412.3 g of solution we have 155 g of KOH

In 100 g of solution, we would have (100 . 155) / 2412.3 = 6.42 %mass percent.

7 0

3 years ago

What is the molarity of formaldehyde in a solution containing 0.25 grams of formaldehyde per mL?

Vikentia [17]

Answer:

8.33mol/L

Explanation:

First, let us calculate the molar mass of of formaldehyde (CH2O). This is illustrated below:

Molar Mass of CH2O = 12 + (2x1) + 16 = 12 + 2 + 16 = 30g/mol

Mass of CH2O from the question = 0.25g

Number of mole CH2O =?

Number of mole = Mass /Molar Mass

Number of mole of CH2O = 0.25/30 = 8.33x10^-3mole

Now we can calculate the molarity of formaldehyde (CH2O) as follow:

Number of mole of CH2O = 8.33x10^-3mole

Volume = 1mL

Converting 1mL to L, we have:

1000mL = 1L

Therefore 1mL = 1/1000 = 1x10^-3L

Molarity =?

Molarity = mole /Volume

Molarity = 8.33x10^-3mole/1x10^-3L

Molarity = 8.33mol/L

Therefore, the molarity of formaldehyde (CH2O) is 8.33mol/L

3 0

3 years ago

Describe the movement of air when you inhale

nikdorinn [45]

When you inhale, air passes through the nasal cavity. There, mucus and hairs clean the air from most foreign particles before entering the body. Then, the air passes from the nasal cavity to the pharynx. After the pharynx, it passes through the larynx reaching the trachea. After passing through the trachea, the air reaches the bronchi, and after the bronchi, the bronchioles that branch off the bronchi. From the bronchioles, the air reaches the alveoli that is when gas exchange happens. O2 enters and CO2 leaves.

3 0

2 years ago