Answer:
- <em>1.34 × 10²⁴ molecules</em>
Explanation:
To calculate the <em>number of molecules of sodium oxide that will be created if 275 grams of sodium reacts with excess oxygen</em>, use the chemical equation to calculate the number of moles and then multiply by Avogadro's number.
<u>1) Balanced chemical equation (given):</u>
<u>2) Mole ratio:</u>
<u>3) Calculate the number of moles in 275 g of Na:</u>
- n = mass in grams / molar mass
- mass of Na = 275 g
- molar mass of Na₂O = 61.9789 g/mol
- n = 275 g / 61.9789 g/mol = 4.437 mol of Na
<u>4) Set a proportion to find the number of moles of product (Na₂O):</u>
- 2 mol Na₂O / 4 mol Na = x / 4.437 mol Na
- x = 4.437 / 2 mol Na₂O = 2.2185 mol Na₂O
<u>5) Convert the number of moles to number of molecules:</u>
- # molecules = n × 6.022 × 10²³ molecules/mol = 2.2185 mol × 6.022 × 10²³ molecules/mol = 1.34 × 10²⁴ molecules (rounded to 3 significant figures).
Answer:
A. 1 liter of water at temperature 75°C
Explanation:
According to kinetic molecular theory average kinetic energy of molecules are directly proportional to absolute temperature.
the quantity of the sample does't depend on kinetic energy only temperature
does so the choice with highest temperature is the correct choice
∵ 1 liter water at 75°C has highest average kinetic energy per molecule
Answer:
Composition of the mixture:
%
%
Composition of the vapor mixture:
%
%
Explanation:
If the ideal solution model is assumed, and the vapor phase is modeled as an ideal gas, the vapor pressure of a binary mixture with 
and 
molar fractions can be calculated as:
Where 
and 
are the vapor pressures of the pure compounds. A substance boils when its vapor pressure is equal to the pressure under it is; so it boils when 
. When the pressure is 0.60 atm, the vapor pressure has to be the same if the mixture is boiling, so:
With the same assumptions, the vapor mixture may obey to the equation:
, where P is the total pressure and y is the fraction in the vapor phase, so:
%
The fractions of B can be calculated according to the fact that the sum of the molar fractions is equal to 1.
