Answer:
3.2 x 10²¹molecules
Explanation:
Given parameters:
Volume of nitrogen gas = 120cm³
Unknown:
Mass of nitrogen gas = ?
Number of molecules = ?
Solution:
To solve this problem, note that;
1 mole of gas occupies a volume of 22.4L at STP
Now;
convert 120cm³ to L ;
1000cm³ = 1L
120cm³ gives 0.12L
Since;
22.4L of gas has 1 mole at STP
0.12L of gas will have 
= 0.0054mole at STP
So;
Mass of N₂ = number of moles x molar mass
Molar mass of N₂ = 2(14) = 28g/mol
Mass of N₂ = 0.0054 x 28 = 0.15g
Now;
1 mole of a gas will have 6.02 x 10²³ molecules
0.0054 mole of N₂ will contain 0.0054 x 6.02 x 10²³ =
3.2 x 10²¹molecules
Via the half-life equation we have:
Where A is the amount initially and final amount after some time has passed, t is the time elapsed, h is the half life time and so:
Therefore there will be 2.8125 grams left after 140 seconds.
PV=nRT<=> P=nRT/V=2,40*R*(273+97)/45 atm.
Calculate it. R is a number that is given, find it and use your math to solve.
Answer:
The correct answer is - They gently shake the pan causing the marbles to move back and forth.
Explanation:
When water is heated the molecules present in its liquid state start to move and vibrate faster and allows the water to expand and increase in volume. If the heat is continuously applied to the water its molecules move even faster and escape in the form of molecules of vapor to the atmosphere.
To exhibit this phenomenon by the marble and pan, Richard and Brooke should gently shake the pan causing the marbles to move back and forth which shows faster vibration and movement of molecules.
The correct answer is B. The concentration of a solution does not decreases when you add more solute to the solvent. Instead, the concentration increases. Concentration is expressed as the amount of solute per unit of solvent. Therefore, increasing the solute, increases this value and increasing the solvent, decreases this value.
