Confused as heck. please help!

Cortisone consists of molecules, each of which contains 21 atoms of carbon (plus other atoms). the mass percentage of carbon in

GalinKa [24]

Now to solve this problem, we are given the number of atoms therefore we must first convert this into number of moles. We can do this by using the Avogadro’s number. Calculating for number of moles of Carbon:

number of moles Carbon = 21 atoms of carbon (1 mole / 6.022 x 10^23 atoms C)

number of moles Carbon = 3.49 x 10^-23 mol C

Converting this to mass by multiplying the molar mass of C:

mass Carbon = 3.49 x 10^-23 mol C (12 g / mol)

mass Carbon = 4.18 x 10^-22 g

Therefore the mass of one molecule of Cortisone is:

mass of 1 molecule Cortisone = 4.18 x 10^-22 g / 0.6998

mass of 1 molecule Cortisone = 5.98 x 10^-22 g per molecule

Converting this to mass per 1 mol of Cortisone, by using again the Avogadro’s number:

mass of 1 mol Cortisone = (5.98 x 10^-22 g / molecule) (<span>6.022 x 10^23 molecules / mol)</span>

mass of 1 mol Cortisone = 360.10 g / mol = molar mass of cortisone

Answer:

360.10 g / mol

4 0

3 years ago

Magnesium burns in air with a dazzling brilliance to produce magnesium oxide: 2 Mg(s) + O2(g) → 2 MgO(s) How many moles of O2 ar

TEA [102]

Answer:

1.05 mols of O2 gas

Explanation:

For this type of problem, it's important to understand what the balanced Chemical equation tells us:

<h3><u>Balanced Chemical equations</u></h3>

Let's look at the balanced chemical equation:

$2Mg(s)+O_2(g)-- > 2MgO(s)$

This equation two sides of the reaction arrow. On the left are the reactants (things you start with, and that react during the chemical reaction), and on the right side are products (things that are produced during the chemical reaction that you end with).

The numbers in front of each compound tell how many of molecules are involved for a full reaction without anything left over. A "mol" is a large quantity ( $6.022*10^{23}$ ), in this case, of molecules , since it's unlikely you're only taking a single molecule of each substance (it would be so tiny, you wouldn't even know you were doing the reaction).

So,for every 2 moles of Magnesium used, we'll also need 1 mole of Oxygen, and it will produce 2 moles of Magnesium Oxide.

In a way, during the reaction it's almost like 2 moles of Magnesium is equal to 1 mole of Oxygen and is equal to 2 moles of Magnesium Oxide:

$2 mol Mg(s)=1mol O_2(g)=2molMgO(s)$

From here, we can build some unit ratios, to convert between the known quantity of moles we have, and find the unknown quantity of moles that are requested.

<h3><u>Finding the right unit ratio</u></h3>

We know that we are looking at 2.10 mol of Magnesium, so we want a unit ratio with moles of Mg on the bottom. <u>We want to find moles of O2</u>, <u>so we want a unit ratio of moles of O2 on top</u>.

The unit ratio we want is the middle part of the equation, divided by the left part of the equation.

$2 mol Mg(s)=1mol O_2(g)\\\frac{2 mol Mg(s)}{2 mol Mg(s)}=\frac{1mol O_2(g)}{2 mol Mg(s)}\\1=\frac{1mol O_2(g)}{2 mol Mg(s)}$

Since this quantity is 1, it is a unit ratio and can be multiplied to other things to change their units (for this problem).

<h3><u>Finding the answer</u></h3>

Starting with what we know, and multiplying by our unit ratio:

$2.10 mol Mg(s)*\frac{1mol O_2(g)}{2 mol Mg(s)}=1.05mol O_2(g)$

Notice that the units from the first quantity cancel with the units on the bottom of the fraction, leaving only the unit on top of the fraction ... the exact units we wanted!

So, 1.05mols of O2 would be consumed during the reaction if exactly 2.10moles of Magnesium are burned.

4 0

2 years ago

The combining of two atomic nuclei to produce one larger nucleus is called

Naddika [18.5K]

C.
Nuclear fission involves the high energy collision of two atomic nuclei to produce one larger nucleus; this process powers stars.

6 0

4 years ago

Which is not something submersibles do?

astraxan [27]

<span>Collect data about shoreline cliffs, waves, and measurable atmospheric effects.</span>

4 0