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Marat540 [252]
2 years ago
6

Explain why elements and compounds are pure substances

Chemistry
2 answers:
Anna11 [10]2 years ago
8 0
<span>N2 - Element; Pure substance O2 - Element; Pure substance N2O - Compound; Pure Substance Air - Homogeneous; Solution</span>
neonofarm [45]2 years ago
6 0
<span>Elements and compounds are substances because we know exactly what is in them. Elements are only one kind of atom and have a symbol. Compounds have a formula telling us exactly how many of what kind of atom make up that compound

Solutions, homogeneous mixtures, not only contain 2 compounds, but we do not know how much of each. We can make salt water with one grain of salt in a cup of water or a drop of water in a cup of salt. Mixtures do not have a formula because they can be any concentration. </span>
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The half life of radon-222 is 3.8 days. How Much of a 100g sample is left after 15.2 days
professor190 [17]

Answer:  

6.2 g  

Explanation:  

In a first-order decay, the formula for the amount remaining after <em>n</em> half-lives is  

N = \frac{N_{0}}{2^{n}}  

where  

<em>N</em>₀ and <em>N</em> are the initial and final amounts of the substance  

1. Calculate the <em>number of half-lives</em>.  

If t_{\frac{1}{2}} = \text{3.8 da}  

n = \frac{t}{t_{\frac{1}{2}}} = \frac{\text{15.2 da}}{\text{3.8 da}}= \text{4.0}

2. Calculate the <em>final mass</em> of the substance.  

\text{N} = \frac{\text{100 g}}{2^{4.0}} = \frac{\text{100 g}}{16} = \text{6.2 g}

4 0
3 years ago
The compound trimethylamine, (CH3)3N, is a weak base when dissolved in water. Write the Kb expression for the weak base equilibr
Zina [86]

Answer:

Kb = [OH⁻] . [C₃H₉NH⁺] / [ C₃H₉N ]

Explanation:

The equation for the reaction of trimethylamine when it is dissolved in water is:

C₃H₉N  +  H₂O ⇄ C₃H₉NH⁺ + OH⁻   Kb

1 mol of trimethylamine catches a proton from the water in order to produce trimethylamonium.

It is a base, because it give OH⁻ to the medium

Expression for Kb (Molar concentration)

Kb = [OH⁻] . [C₃H₉NH⁺] / [ C₃H₉N ]

7 0
3 years ago
An electron is a particle with a _____.
astra-53 [7]
The Answer is B.

*NEGATIVE CHARGE, FOUND OUTSIDE THE NUCLEUS*
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What is 5.2034 x 10^8 in standard format
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Five hundred twenty million, three hundred and forty thousand. hope it helps!

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3 years ago
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Answer:

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