Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (the stratosphere). Ozone protects life on Earth from the Sun's ultraviolet (UV) radiation.

3 0

3 years ago

If you have a 150-gram sample of CrO3: • How many moles of CrO3 do you have? • How many oxygen atoms do you have? • How many gra

docker41 [41]

Answer :

(a) The moles of $CrO_3$ is, 1.5 moles.

(b) The number of oxygen atoms are, $27.099\times 10^{23}$

(c) The mass of oxygen is, 72 grams.

Explanation : Given,

Mass of $CrO_3$ = 150 g

Molar mass of $CrO_3$ = 100 g/mole

Molar mass of oxygen = 16 g/mole

(a) First we have to calculate the moles of $CrO_3$ .

$\text{Moles of }CrO_3=\frac{\text{Mass of }CrO_3}{\text{Molar mass of }CrO_3}=\frac{150g}{100g/mole}=1.5moles$

The moles of $CrO_3$ is, 1.5 moles.

(b) Now we have to calculate the number of oxygen atoms.

In $CrO_3$ , there are 1 atom of chromium and 3 atoms of oxygen.

According to the mole concept,

1 mole of $CrO_3$ contains $3\times 6.022\times 10^{23}$ number of oxygen atoms.

So, 1.5 mole of $CrO_3$ contains $1.5\times 3\times 6.022\times 10^{23}=27.099\times 10^{23}$ number of oxygen atoms.

The number of oxygen atoms are, $27.099\times 10^{23}$

(c) Now we have to calculate the mass of oxygen.

As, 1 mole of $CrO_3$ contains 3 moles of oxygen

So, 1.5 mole of $CrO_3$ contains $1.5\times 3=4.5$ moles of oxygen

$\text{Mass of oxygen}=\text{Moles of oxygen}\times \text{Molar mass of oxygen}$

$\text{Mass of oxygen}=(4.5mole)\times (16g/mole)=72g$

The mass of oxygen is, 72 grams.

3 0

3 years ago

What is the percent by mass of chlorine in NaCi? total mass of element in compound molar mass of compound Use %Element x 100

jekas [21]

What is the percent by mass of chlorine in NaCi? total mass of element in compound molar mass of compound Use %Element x 100

7 0

2 years ago

What is the energy change when the temperature of 14.8 grams of solid lead is decreased from 38.4 °C to 23.7 °C ?

zimovet [89]

Answer: Q= -34.6 J

Explanation: Use Q= mc∆T

c for solid lead is equal to 0.159 J/g°C

Substitute the values:

=14.8 g(0.159J/g°C)(23.7°C-38.4 °C)

= 14.8 g(0.159J/g°C) ( -14.7°C)

= -34.6 J

Cancel out the following units: g and °C so the remaining unit is in J.

8 0

3 years ago