There are 8.61 × 10²⁰ atoms in 0.290 g P₂O₅.
Step 1. Convert <em>grams of P₂O₅ to moles of P₂O₅</em>.

Step 2. Convert <em>moles of P₂O₅ to molecules of P₂O₅</em>.


Step 3. Convert <em>molecules of P₂O₅ to atoms</em>.
There are seven atoms in 1 mol P₂O₅.
∴ 
Combustion reaction
Key: O2
O2 is normally in a chemical formula when you are used to burn anything, so basically, anything with O2 involves burning.
If 1mole ------------- is ---------------- 6.02*10²³
than 0.25mole ----- is ---------------- x
x = [0.25mole*6.02*10²³]/1mole = <u>1,505*10²³</u>
Answer:
0.5188 M or 0.5188 mol/L
Explanation:
Concentration is calculated as <u>molarity</u>, which is the number of moles per litre.
***Molarity is represented by either "M" or "c" depending on your teacher. I will use "c".
The formula for molarity is:
n = moles (unit mol)
V = volume (unit L)
<u>Find the molar mass (M) of potassium hydroxide.</u>

<u>Calculate the moles of potassium hydroxide.</u>


Carry one insignificant figure (shown in brackets).
<u>Convert the volume of water to litres.</u>


Here, carrying an insignificant figure doesn't change the value.
<u>Calculate the concentration.</u>

<= Keep an insignificant figure for rounding
<= Rounded up
<= You use the unit "M" instead of "mol/L"
The concentration of this standard solution is 0.5188 M.
Answer:
V = 34.55 L
Explanation:
Given that,
No of moles, n = 1.4
Temperature, T = 20°C = 20 + 273 = 293 K
Pressure, P = 0.974 atm
We need to find the volume of the gas. It can be calculated using Ideal gas equation which is :
PV=nRT
R is gas constant, 
Finding for V,

So, the volume of the gas is 34.55 L.