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3 years ago

Balance of Atoms Quick Check

Chemistry

2 answers:

castortr0y [4]3 years ago

7 0

Answer:

Explanation:

I took the test

san4es73 [151]3 years ago

3 0

When iron rusts and forms iron oxide, the iron oxide has more mass than the iron because there are more iron atoms in iron oxide than in pure iron.

The process of rust occurs when pure iron is exposed to air and moisture. Rust is the oxidation of pure iron to iron II oxide (Fe2O3).

We can see that there are two iron atoms per mole of Fe2O3 whereas there is only one iron atom in each mole of pure iron.

Therefore, iron oxide has more mass than the iron because there are more iron atoms in iron oxide than in pure iron.

Learn more; brainly.com/question/18376414

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How many hydrogen atoms are in 105 g of water?

mel-nik [20]

Moles of water atoms = mass/molecular weight = 105/18 = 5.83 mol. Number of moles of hydrogen in water = 2 x moles of water = 11.66. Number of H atoms in water = moles of hydrogen x 6.02 x 10^23 = 7.019 x 10^24 ~ 7.02 x 10^24 atoms. Hope this helps.

3 0

3 years ago

What must be the molarity of an aqueous solution of trimethylamine, (ch3)3n, if it has a ph = 11.20? (ch3)3n+h2o⇌(ch3)3nh++oh−kb

Stolb23 [73]

0.040 mol / dm³. (2 sig. fig.)

<h3>Explanation</h3>

$(\text{CH}_3)_3\text{N}$ in this question acts as a weak base. As seen in the equation in the question, $(\text{CH}_3)_3\text{N}$ produces $\text{OH}^{-}$ rather than $\text{H}^{+}$ when it dissolves in water. The concentration of $\text{OH}^{-}$ will likely be more useful than that of $\text{H}^{+}$ for the calculations here.

Finding the value of $[\text{OH}^{-}]$ from pH:

Assume that $\text{pK}_w = 14$ ,

$\begin{array}{ll}\text{pOH} = \text{pK}_w - \text{pH} \\ \phantom{\text{pOH}} = 14 - 11.20 &\text{True only under room temperature where }\text{pK}_w = 14 \\\phantom{\text{pOH}}= 2.80\end{array}$ .

$[\text{OH}^{-}] =10^{-\text{pOH}} =10^{-2.80} = 1.59\;\text{mol}\cdot\text{dm}^{-3}$ .

Solve for $[(\text{CH}_3)_3\text{N}]_\text{initial}$ :

$\dfrac{[\text{OH}^{-}]_\text{equilibrium}\cdot[(\text{CH}_3)_3\text{NH}^{+}]_\text{equilibrium}}{[(\text{CH}_3)_3\text{N}]_\text{equilibrium}} = \text{K}_b = 1.58\times 10^{-3}$

Note that water isn't part of this expression.

The value of Kb is quite small. The change in $(\text{CH}_3)_3\text{N}$ is nearly negligible once it dissolves. In other words,

$[(\text{CH}_3)_3\text{N}]_\text{initial} = [(\text{CH}_3)_3\text{N}]_\text{final}$ .

Also, for each mole of $\text{OH}^{-}$ produced, one mole of $(\text{CH}_3)_3\text{NH}^{+}$ was also produced. The solution started with a small amount of either species. As a result,

$[(\text{CH}_3)_3\text{NH}^{+}] = [\text{OH}^{-}] = 10^{-2.80} = 1.58\times 10^{-3}\;\text{mol}\cdot\text{dm}^{-3}$ .

$\dfrac{[\text{OH}^{-}]_\text{equilibrium}\cdot[(\text{CH}_3)_3\text{NH}^{+}]_\text{equilibrium}}{[(\text{CH}_3)_3\text{N}]_\textbf{initial}} = \text{K}_b = 1.58\times 10^{-3}$ ,

$[(\text{CH}_3)_3\text{N}]_\textbf{initial} =\dfrac{[\text{OH}^{-}]_\text{equilibrium}\cdot[(\text{CH}_3)_3\text{NH}^{+}]_\text{equilibrium}}{\text{K}_b}$ ,

$[(\text{CH}_3)_3\text{N}]_\text{initial} =\dfrac{(1.58\times10^{-3})^{2}}{6.3\times10^{-5}} = 0.040\;\text{mol}\cdot\text{dm}^{-3}$ .

8 0

3 years ago

in a mixture of 1.90 mol of gas, 0.85 mol are nitrogen (n2) molecules. what is the mole fraction of n2 in this mixture?

Nostrana [21]

0.447 is the mole fraction of Nitrogen in this mixture.

mole fraction of nitrogen= moles of nitrogen/total moles

mole fraction of nitrogen=0.85/1.90

mole fraction of nitrogen=0.447

The product of the moles of a component and the total moles of the solution yields a mole fraction, which is a unit of concentration measurement. Because it is a ratio, mole fraction is a unitless statement. The sum of the components of the mole fraction of a solution is one. In a mixture of 1 mol benzene, 2 mol carbon tetrachloride, and 7 mol acetone, the mole fraction of the acetone is 0.7. This is computed by dividing the sum of the moles of acetone in the solution by the total number of moles of the solution's constituents:

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4 0

1 year ago

Which one of the following statements explains why mass is lost when a student heats a sample of BaCl₂ • 2H₂O crystals?

inessss [21]

Answer:

where are the statements??

Explanation:

7 0

3 years ago

A substance intentionally added that affects the nature and quality of food is called.

VashaNatasha [74]

A substance intentionally added that affects the nature and quality of food is called food material.

There are seven most important components in food materials: carbohydrates, fats, proteins, vitamins, mineral salts, water and fibre.

Some other examples of food material:

1) Food dyes are chemical substances who gives artificial color to the food.

It is important to know which food dyes are in food because some dyes can cause allergic reactions or cancer.

2) Emulgators are used as an additive to food to emulsify some food.

Emulsions are two or more liquids that are normally not mixable. For example egg yolk and mayonnaise.

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6 0

1 year ago