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3 years ago

The answer ........................... ..

Chemistry

1 answer:

algol [13]3 years ago

5 0

assuming the question is 2. you add a prefix to the base unit, it shows it right there. Depending on how much larger or smaller the prefix changes from mega-micro.

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12. How many moles of atoms are present in 154 g of Na2O?

tia_tia [17]

Answer:

$\boxed {\boxed {\sf A. \ 2.48 \ mol \ Na_2O}}$

Explanation:

We are asked to convert an amount in grams to moles. To do this, we use the molar mass. This is the number of grams in one mole of a substance. It is the same value numerically as the atomic mass on the Periodic Table, however the units are grams per mole, not atomic mass units.

Look up the molar masses for the individual elements.

Sodium (Na): 22.9897693 g/mol
Oxygen (O): 15.999 g/mol

Look back at the formula: Na₂O. Notice there is a subscript of 2 after sodium. This means there are 2 atoms of sodium in every molecule, so we have to multiply sodium's molar mass by 2 before adding oxygen's.

Na₂O: 2(22.9897693 g/mol)+ 15.999 g/mol = 61.9785386 g/mol

Set up a ratio using the molar mass.

$\frac {61.9785386 \ g \ Na_2O}{1 \ mol \ Na_2O}$

Multiply by the given number of grams.

$154 \ g \ Na_2O*\frac {61.9785386 \ g \ Na_2O}{1 \ mol \ Na_2O}$

Flip the ratio so the grams of sodium oxide can cancel each other out.

$154 \ g \ Na_2O*\frac {1 \ mol \ Na_2O}{61.9785386 \ g \ Na_2O}$

$154 *\frac {1 \ mol \ Na_2O}{61.9785386 }$

$\frac {154}{61.9785386 } \ mol \ Na_2O$

$2.48473106141 \ mol \ Na_2O$

The original measurement of grams given has 3 significant figures, so our answer must have the same. For the number we calculated, that is the hundredth place.

2.48<u>4</u>73106141

The 4 in the thousandth place tells us to leave the 8.

$2.48 \ mol \ Na_2O$

There are <u>2.48 moles of sodium oxide</u> in 154 grams, so choice A is correct.

6 0

3 years ago

During the light-independent reaction, carbon dioxide is fixed by adding it to a A. 2-carbon compound B. 3-carbon compound C. 4-

Scrat [10]

During the light independent reaction, carbon dioxide is fixed by adding it to a <span>5-carbon compound</span>

8 0

3 years ago

Read 2 more answers

What is the pH of a solution with [H+] of 1x10^-8 M?*<br> 15<br> -8<br> 8<br> 80

Serga [27]

Answer:

Explanation:

The pH of a solution can be found by using the formula

$pH = - log [ {H}^{+} ]$

From the question we have

$ph = - log(1 \times {10}^{ - 8} ) \\ = 8$

We have the final answer as

Hope this helps you

3 0

3 years ago

The solution set of axequalsb is the set of all vectors of the form wequalspplusbold v subscript h, where bold v subscript h is

ELEN [110]

Answer : Incorrect

Explanation : In the given solution set of Ax = b;
is set of all vectors to form w= p + $V_{h}$
here $V_{h}$ is is any solution of the equation Ax = 0;

this stands to be incorrect, as the correct would only exists when some vector p is found to be like this Ap=b

3 0

4 years ago

Which one of the following chemicals does the body generate during regular exercise?

Slav-nsk [51]

B. Endorphins are released during exercise

7 0

3 years ago