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3 years ago

Which expression represents this word phrase?

2 answers:

6 0

Answer: B

The quotient is what you get when you divide two numbers by each other so therefore x divided by 9. And then 7 less than that number

Allushta [10]3 years ago

5 0

Answer:

B. (x÷9)-7

Explanation:

The quotient is the answer of division, therefore we know that x is divided by 9. We know which is divided by which because of the order the phrase is written. So far we have:

x ÷ 9

Now we subtract seven because the phrase states that it is seven less then the quotient. Therfore our answer is:

(x ÷ 9) - 7

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write the net ionic equation (including phases) that corresponds to Cu(ClO4)2(aq) + Na2CO3(aq)-------->CaCO3(s) + 2NaClO4(aq)

soldier1979 [14.2K]

Complete ionic:
Cu(aq) + 2Cl(aq) + 8O(aq) + 2Na(aq) + C(aq) + 3O(aq) = CaCO3(s) + 2Na(aq) + Cl(aq) + 4O(aq)

Net ionic:

Cu(aq) + Cl(aq) + 4O(aq) + 2Na(aq) + C(aq) + 3O(aq) = CaCO3(s)

So write everything out as IF it will dissociate in water. So everything that is aq splits but solid just floats to the bottom of the mixture. Cancel what you can (in this case the two from the ClO4 on the left of the equation cancels with the ClO4 from the right) and the 2Na cancels. Then, write out the whole solution and you are done!

3 0

2 years ago

0.50 g of hydrogen chloride (HCl) is dissolved in water to make 4.0 L of solution. What is the pH of the resulting hydrochloric

svlad2 [7]

Explanation:

Given the mass of HCl is ---- 0.50 g

The volume of solution is --- 4.0 L

To determine the pH of the resulting solution, follow the below-shown procedure:

1. Calculate the number of moles of HCl given by using the formula:

$number of moles of a substance=\frac{given mass of the substance}{its molecular mass}$

2. Calculate the molarity of HCl.

3. Calculate pH of the solution using the formula:

$pH=-log[H^+]$

Since HCl is a strong acid, it undergoes complete ionization when dissolved in water.

$HCl(aq)->H^+(aq)+Cl^-(aq)$

Thus, $[HCl]=[H^+]$

Calculation:

1. Number of moles of HCl given:

$number of moles of a substance=\frac{given mass of the substance}{its molecular mass}\\=0.50g/36.5g/mol\\=0.0137mol$

2. Concentration of HCl:

$Molarity of HCl=\frac{number of moles of HCl}{its molar mass}\\=\frac{0.0137 mol}{4.0 L} \\= 0.003425 M$

3. pH of the solution:

$pH=-log[H^+]\\=-log(0.003425)\\=2.47$

Hence, pH of the given solution is 2.47.

3 0

3 years ago

When science is used to create a new instrument, such as a cell phone, we say that a new ___________ has been developed.

kari74 [83]

Is it Technology? What have you already tried?

3 0

3 years ago

a chemist dissolved an 11.9-g sample of koh in 100.0 grams of water in a coffee cup calorimeter. when she did so, the water temp

Snowcat [4.5K]

The heat of solution is -51.8 kJ/mol

<h3>What is the heat of solution?</h3>

We know that in a calorimeter, there is no loss or gain of energy. It is a good example of a closed system.

Number of moles of KOH = 11.9-g/56 g/mol = 0.21 moles

Temperature rise = 26.0 ∘c

Mass of the water = 100.0 grams

Heat capacity = 4.184 j/g⋅°c

Then;

ΔH = mcθ

ΔH = 100g * 4.184 j/g⋅°c * 26.0 ∘c = 10.88 kJ

Heat of solution = -(10.88 kJ/ 0.21 moles) = -51.8 kJ/mol

Learn more about heat of solution:brainly.com/question/24243878

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4 0

2 years ago

Complete the acid–base equation for the dissolution of the following compound into liquid HF solvent. The relevant pKa values ar

LenKa [72]

Answer:

The balanced chemical equation: NH₃ + 2 HF → NH₄⁺ + HF₂⁻

Explanation:

According to the Brønsted–Lowry acid–base theory, the acid- base reaction is a type of chemical reaction between the acid and base to give a conjugate acid and a conjugate base.

In this reaction, a Brønsted–Lowry acid loses a proton to form a conjugate base. Whereas, a Brønsted–Lowry base accepts a proton to form a conjugate acid.

Acid + Base ⇌ Conjugate Base + Conjugate Acid

The acid dissociation constant (Kₐ) <em>signifies the acidic strength of a chemical species.</em>

∵ pKₐ = - log Kₐ

Thus for a strong acid, Kₐ value is large and pKₐ value is small.

pKₐ (HF) = 3.2 → strong acid

pKₐ (NH₃) = 38 → weak acid

<u>The chemical reaction involved in the dissolution process:</u>

NH₃ + 2 HF → NH₄⁺ + HF₂⁻

In this acid-base reaction, the acid HF reacts with NH₃ base to give the conjugate base HF₂⁻ and conjugate acid NH₄⁺.

<u>HF (acid) donates a proton to form the conjugate base, HF₂⁻ ion. NH₃ (base) accepts a proton to form the conjugate acid. </u>

7 0

3 years ago