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3 years ago

When thermal energy is added to an object, what happens to the motion of the particles?

Chemistry

1 answer:

Novay_Z [31]3 years ago

3 0

The atoms start vibrating faster

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Given the reaction below which of the following best describes the energy changes in this reaction?

insens350 [35]

Answer:

first choice

Explanation:

energy is written on the left side is its absorbed

2 elements came together so bonds are formed.

8 0

3 years ago

Write a hypothesis statement about the relationship between the number of mushrooms and the concentration of heavy metals in the

Anna007 [38]

Answer:

Write a hypothesis statement about the relationship between the number of mushrooms and the concentration of heavy metals in the soil ...

8 0

2 years ago

How many moles are in 3.45g of KCI ?

artcher [175]

<h3>Answer:</h3>

0.0463 mol KCl

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

<u>Chemistry</u>

<u>Atomic Structure</u>

Reading a Periodic Table
Using Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

3.45 g KCl

<u>Step 2: Identify Conversions</u>

Molar Mass of K - 39.10 g/mol

Molar Mass of Cl - 35.45 g/mol

Molar Mass of KCl - 39.10 + 35.45 = 74.55 g/mol

<u>Step 3: Convert</u>

Set up: $\displaystyle 3.45 \ g \ KCl(\frac{1 \ mol \ KCl}{74.55 \ g \ KCl})$
Multiply/Divide: $\displaystyle 0.046278 \ mol \ KCl$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 3 sig figs.</em>

0.046278 mol KCl ≈ 0.0463 mol KCl

8 0

3 years ago

How many moles of methane are in 7.31x10^25 molecules?

lana [24]

Answer:

121.37 moles.

Explanation:

Always one mole of any molecule contains Avogadro number of molecules.

So one mole of methane contains 6.023*10^23 molecules.

Now we need number of moles of methane in 7.31*10^25 molecules.

This is just cross multiplication stuff.

6.023*10^23 molecules —————- 1 mole

7.31*10^25 molecules ——————- ?

= (7.31*10^25) / (6.023*10^23)

= 121.37 moles.

8 0

3 years ago

Atypicalaspirintabletcontains325mgofacetylsalicylic acid (HC9H7O4). Calculate the pH of a solution that is prepared by dissolvin

Sergio [31]

Answer:

$\boxed{2.65}$

Explanation:

1. Mass of acetylsalicylic acid (ASA)

$m = \text{2 tablets} \times \dfrac{\text{325 mg}}{\text{1 tablet}} = \text{750 mg}$

2. Moles of ASA

HC₉H₇O₄ =180.16 g/mol

$n = \text{750 mg} \times \dfrac{\text{1 mmol}}{\text{180.16 mg }} = \text{4.163 mmol}$

3. Concentration of ASA

$c = \dfrac{\text{4.163 mmol}}{\text{237 mL}} = \text{0.01757 mol/L}$

4. Set up an ICE table

$\begin{array}{ccccccc}\text{HA} & + & \text{H$_{2}$O}& \, \rightleftharpoons \, &\text{H$_{3}$O$^{+}$} & + &\text{A}^{-}\\0.01757 & & & &0 & & 0 \\-x & & & &+x & & +x \\0.01757-x & & & &x & & x \\\end{array}\\$

5. Solve for x

$K_{\text{a}} = \dfrac{\text{[H}_{3}\text{O}^{+}]\text{A}^{-}]} {\text{[HA]}} = 3.33 \times 10^{-4}\\\\\dfrac{x^{2}}{0.01757 - x} = 3.33 \times 10^{-4}\\\\\textbf{Check that }\mathbf{x \ll 0.01757}\\\\\dfrac{ 0.01757 }{3.33 \times 10^{-4}} = 53 < 400\\\\\text{The ratio is less than 400. We must solve a quadratic equation.}\\\\x^{2} = 3.33 \times 10^{-4}(0.01757 - x) \\\\x^{2} = 5.851 \times 10^{-6} - 3.33 \times 10^{-4}x\\\\x^{2} + 3.33 \times 10^{-4}x - 5.851 \times 10^{-6} = 0$

6. Solve the quadratic equation.

$a = 1; b = 3.33 \times 10^{-4}; c = -5.851 \times 10^{-6}$

$x = \dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\\text{Substituting values into the formula, we get}\\x = 0.002258\qquad x = -0.002591\\\text{We reject the negative value, so}\\x = 0.002258$

7. Calculate the pH

$\rm [H_{3}O^{+}]= x \, mol \cdot L^{-1} = 0.002258 \, mol \cdot L^{-1}\\\text{pH} = -\log{\rm[H_{3}O^{+}]} = -\log{0.002258} = \mathbf{2.65}\\\text{The pH of the solution is } \boxed{\textbf{2.65}}$

4 0

3 years ago