In an average mass, each entry has equal weight. In a weighted average, we multiply each entry by a number representing its relative importance.
Assume that your class consists of 15 girls and 5 boys. Each girl has a mass of 54 kg, and each boy has a mass of 62 kg.
<em>Average mass</em> = (girl + boy)/2 = (54 kg + 62 kg)/2 = <em>58 kg</em>
<em>Weighted average (Method 1)
</em>
Use the <em>numbers of each</em> gender (15 girls + 5 boys)
,
Weighted average = (15×54 kg + 5×62 kg)/20 = (810 kg + 310 kg)/20
= 1120 kg/20 = <em>56 kg</em>.
If you put all the students on one giant balance, their total mass would be
1120 kg and the average mass of a student would be <em>56 kg.
</em>
<em>Weighted average (Method 2)
</em>
Use the <em>relative percentages</em> of each gender (75 % girls and 25 % boys).
Weighted average = 0.75×54 kg + 0.25×62 kg = 40.5 kg + 15.5 kg = <em>56 kg</em>
Each girl contributes 40.5 kg and each boy contributes 15.5 kg to the <em>weighted average</em> mass of a student.
Answer is 0.10 mol.
<em>Explanation;</em>
n = m/M
Where n is number of moles (mol), m is the mass of substance (g) and M is the molar mass of the substance (g/mol).
n = ?
m = 0.40 g
M = 4.0 g/mol
From substitution,
n = 0.40 g /4.0 g/mol
n = 0.10 mol
Hence, the balloon has 0.10 mol of He.
Answer:
A
Explanation:
You want an equation that includes both V and T. Charles' Law states that V =kT or V₁/T₁ = V₂/T₂, so this is the best formula to use.
B: The Combined Gas Law is p₁V₁/T₂ = p₂V₂/T₂ will work, but it's overkill for the situation. You can assume any constant value for the pressure, and it will cancel from each side of the equation,
C is wrong. Boyle's Law is p₁V₁ = p₂V₂. It does not include the temperature.
D is wrong. Gay-Lussac's Law is p₁/T₂ = p₂/T₂. It does not include the volume.
Answer:
The formula for lithium acetate is CH3COOLi
Explanation:
The formula for lithium acetate is obtained by replacing the hydrogen atom bonding to the oxygen atom in acetic acid with Li as shown below:
CH3COOH + LiOH —> CH3COOLi + H2O
