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2 years ago

Which element has fewer than four dots in its electron dot diagrams?

Chemistry

2 answers:

Karolina [17]2 years ago

6 0

The answer is Gallium (Ga)

Igoryamba2 years ago

3 0

Answer:

Gallium (Ga)

Explanation:

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Glycolic acid, which is a monoprotic acid and a constituent in sugar cane, has a pKa of 3.9. A 25.0 mL solution of glycolic acid

Phoenix [80]

Answer:

pH = 8.0

Explanation:

First, we have to calculate the moles of NaOH.

$35.8 \times 10^{-3}L.\frac{0.020mol}{L} =7.2\times 10^{-4}mol$

Let's consider the balanced equation.

C₂H₄O₃ + NaOH ⇒ C₂H₃O₃Na + H₂O

The molar ratio C₂H₄O₃: NaOH: C₂H₃O₃Na is 1: 1: 1. So, when 7.2 × 10⁻⁴ moles of NaOH react completely with 7.2 × 10⁻⁴ moles of C₂H₄O₃ they form 7.2 × 10⁻⁴ moles of C₂H₃O₃Na.

The concentration of C₂H₃O₃Na is:

$\frac{7.2\times 10^{-4}mol}{60.8 \times 10^{-3}L} =0.012M$

C₂H₃O₃Na dissociates according to the following equation:

C₂H₃O₃Na(aq) ⇒ C₂H₃O₃⁻(aq) + Na⁺(aq)

C₂H₃O₃⁻ comes from a weak acid so it undergoes basic hydrolisis.

C₂H₃O₃⁻ + H₂O ⇄ C₂H₄O₃ + OH⁻

If we know that pKa for C₂H₄O₃ is 3.9, we can calculate pKb for C₂H₃O₃⁻ using the following expression:

pKa + pKb = 14

pKb = 14 -3.9 = 10.1

10.1 = -log Kb

Kb = 7.9 × 10⁻¹¹

We can calculate [OH⁻] using the following expression:

[OH⁻] = √(Kb.Cb) <em>where Cb is the initial concentration of the base</em>

[OH⁻] = √(7.9 × 10⁻¹¹ × 0.012M) = 9.7 × 10⁻⁷ M

Now, we can calculate pOH and pH.

pOH = -log [OH⁻] = -log (9.7 × 10⁻⁷) = 6.0

pH + pOH = 14

pH = 14 - pOH = 14 - 6.0 = 8.0

7 0

2 years ago

Measurements show that unknown compound X has the following composition: element mass % carbon 41.0% hydrogen 4.58% oxygen 54.6%

anastassius [24]

Answer:

CHO

Explanation:

Carbon = 41%, Hydrogen = 4.58%, oxygen = 54.6%

Step 1:

Divide through by their respective relative atomic masses

41/ 12, 4.58/1, 54.6/16

3.41 4.58 3.41

Step 2:

Divide by the lowest ratio:

3.41/3.41, 4.58/3.41, 3.41/3.41

1, 1, 1

Hence the empirical formula is CHO

8 0

2 years ago

If the half-life of a radioactive substances is 590 million years and you have 40 atoms of it, how many half-lives will have pas

Nady [450]

Answer:

Explanation:

Applying,

$2^{n'}$ = R/R'............... Equation 1

Where n' = number of halflives that have passed, R = Original atom of the substance, R' = atom of the substance left after decay.

From the question,

Given: R = 40 atoms, R' = 5 atoms

Substitute these values into equation 1

$2^{n'}$ = 40/5

$2^{n'}$ = 8

$2^{n'}$ = 2³

Equation the base,

n' = 3

3 0

2 years ago

What is the molarity of a solution that contains 0.082 mol KI in a 2.03 L solution?

astraxan [27]

Answer:

molarity of the KI solution = 0.04 mol/L

Explanation:

Molarity (M) is the concentration of a solution expressed as the number of moles of solute per liter of solution.

The law that we can applied to calculate the M is:

M = n / V

n - number of moles

V- volume of the solution (liters)

Then insert in the equation the values from the question;

M = 0.082 mol / 2.03 L = 0.04 mol/L

4 0

2 years ago

Is melting sugar a chemical or physical change? Please provide an explanation

liraira [26]

Answer:

Hola Amigo! Here's Ur Answer :D

Explanation:

The chemical reaction we are most familiar with is that of melting: sugar decomposes at a temperature ranging between 184 and 186°C. This is a very recent discovery we owe to a team of researchers in Illinois. Basically, when we heat sucrose gently, this produces a phenomenon known as “ apparent melting ”.

Happy to Help! :D

3 0

3 years ago

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