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2 years ago

What is Chemistry????

2 answers:

7 0

Chemistry is the scientific study of the properties and behaviour of matter. It is a natural science that covers the elements that make up matter to the compounds composed of atoms, molecules and ions: their composition, structure, properties, behaviour and the changes they undergo during a reaction with other substances.

prisoha [69]2 years ago

5 0

Answer:

Chemistry is the scientific study of matter and its properties

Explanation:

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Which system of measurement does the U.S. use?????

nasty-shy [4]

U.S customary system

8 0

3 years ago

How many formula units make up 24.2 g of magnesium chloride (MgCl2)? Help!!

NNADVOKAT [17]

Answer:

Approximately $1.53 \times 10^{23}$ formula units ( $0.254\; \rm mol$ ).

Explanation:

Refer to a modern periodic table for the relative atomic mass of magnesium ( $\rm Mg$ ) and chlorine ( $\rm Cl$ ):

$\rm Mg$ : $24.305$ .
$\rm Cl$ : $35.45$ .

In other words, the mass of $1\; \rm mol$ of $\rm Mg$ atoms would be (approximately) $24.305\; \rm g$ .

Likewise, the mass of $1\; \rm mol$ of $\rm Cl$ atoms would be approximately $35.45\; \rm g$ .

One formula unit of the ionic compound $\rm MgCl_{2}$ includes exactly as many atoms as there are in the given formula. The formula mass of a compound is the mass of $1\; \rm mol$ of the formula units of this compound.

The formula $\rm MgCl_{2}$ includes one $\rm Mg$ atom and two $\rm Cl$ atoms.

Hence, every formula unit of $\rm MgCl_{2} \!$ would include the same number of atoms: one $\rm Mg\!$ atom and two $\rm Cl\!$ atoms. There would be $1\; \rm mol$ of $\rm Mg$ atoms and $2\; \rm mol$ of $\rm Cl$ atoms in $1\; \rm mol\!$ of $\rm MgCl_{2}$ formula units.

Thus, the mass of $1\; \rm mol\!$ of $\rm MgCl_{2}$ formula units would be equal to the mass of $1\; \rm mol$ of $\rm Mg$ atoms plus the mass of $2\; \rm mol$ of $\rm Cl$ atoms. (The mass of $1\; \rm mol\!\!$ of each atom could be found from the relative atomic mass of each element.)

$\begin{aligned}& M({\rm MgCl_{2}}) \\ =\; & 24.305\; {\rm g \cdot mol^{-1}} + 2\times {\rm 35.45 \; \rm g \cdot mol^{-1}} \\ =\; & 95.205\; \rm g \cdot mol^{-1}\end{aligned}$ .

In other words, the formula mass of $\rm MgCl_{2}$ is $95.205\; \rm g \cdot mol^{-1}$ .

Therefore, the number of formula units in $m = 24.2\; \rm g$ of $\rm MgCl_{2}$ would be:

$\begin{aligned}n &= \frac{m({\rm MgCl_{2}})}{M({\rm MgCl_{2}})} \\ &= \frac{24.2\; \rm g}{95.205\; \rm g\cdot mol^{-1}} \\ & \approx 0.254\; \rm mol\end{aligned}$ .

Multiple $n$ by Avogadro's Number $N_{A} \approx 6.022 \times 10^{23}\; \rm mol^{-1}$ to estimate the number of formula units in $0.254\; \rm mol$ :

$\begin{aligned}N &= n \cdot N_{A} \\ &\approx 0.254\; \rm mol \times 6.022 \times 10^{23}\; \rm mol^{-1} \\ &\approx 1.53\times 10^{23}\end{aligned}$ .

6 0

3 years ago

A .......... notifies you that danger is present if the directions are not followed.

maksim [4K]

Answer:

A. Warning

Explanation:

Out of all said choices, the best choice would be warning since it would fit the sentence the most.

"A Warning notifies you that danger is present." compared to:

"A Hazard notifies you that danger is present."

"A Safety notifies you that danger is present."

"A Danger notifies you that danger is present."

5 0

3 years ago

Which is an expression? A. 1 = 3 - 2 B. 2 + 5 = 5 + 2 C. 4+ 3 < 9 D. 26

Helga [31]

Answer:

A. 1 = 3 - 2

Explanation:

What defines an expression?

expression - An expression is a sentence with a minimum of two numbers and at least one math operation. This math operation can be addition, subtraction, multiplication, and division.

So if we look at the letter options we can see that A is the best choice.

3 0

3 years ago

Read 2 more answers

In your own words, explain why we have seasons on Earth. Why do some places have all 4 seasons and others seem to only have 1 or

Ber [7]

We have seasons on earth because of the way the earth is tilt on its axis. at a certain time in the year, the sun's rays reach certain parts of the globe more than others.

some places have 4 seasons because they are in the northern hemisphere, which is in the sweet spot of the sun's rays that give us each season. other places only have 1 or 2 because they are not in the northern hemisphere.

7 0

3 years ago

What is Chemistry????​

What is Chemistry????