Answer:
c : 13%
Explanation:
Data Give:
Experimental density of vanadium = 6.9 g/cm³
percent error = ?
Solution:
Formula used to calculate % error
% error = [experimental value -accepted value/accepted value] x 100
The reported accepted density value for vanadium = 6.11 g/cm³
Put value in the above equation
% error = [ 6.9 - 6.11 / 6.11 ] x 100
% error = [ 0.79 / 6.11 ] x 100
% error = [ 0.129] x 100
% error = 12.9
Round to the 2 significant figure
% error = 13 %
So, option c is correct
We need to first find the molarity of Ba(OH₂) solution.
A mass of 3.24 mg is dissolved in 1 L solution.
Ba(OH)₂ moles dissolved - 3.24 x 10⁻³ g/171.3 g/mol = 1.90 x 10⁻⁵ mol
dissociaton of Ba(OH)₂ is as follows;
Ba(OH)₂ --> Ba²⁺ + 2OH⁻
1 mol of Ba(OH)₂ dissociates to form 2OH⁻ ions.
Therefore [OH⁻] = (1.90 x 10⁻⁵)x2 = 3.8 x 10⁻⁵ M
pOH = -log[OH⁻]
pOH = -log (3.8 x 10⁻⁵)
pOH = 4.42
pH + pOH = 14
therefore pH = 14 - 4.42
pH = 9.58
Answer: 2800 g
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number 
of particles.
Given mass = 5 kg = 5000 g
1 mole of 
produces = 1 mole of 
50 moles of produces =
of
Mass of 
2800 g of is produced from 5.0 kg of limestone.
You need to find the abundance. Then, multiply the abundance by 100, and add that to the mass for each isotope. Basically, for each isotope, take the percentage abundance and add it to the mass. Multiply each calculation of these together to get your average atomic mass,
Step 1 : Write balanced chemical equation.
CaF₂ can be converted to F₂ in 2 steps. The reactions are mentioned below.
I] 
II] 
The final balanced equation for this reaction can be written as
Step 2: Find moles of CaF₂ Using balanced equation
We have 1.12 mol F₂
The mole ratio of CaF₂ and F₂ is 1:1
Step 3 : Calculate molar mass of CaF2.
Molar mass of CaF₂ can be calculated by adding atomic masses of Ca and F
Molar mass of CaF₂ = Ca + 2 (F)
Molar mass of CaF₂ = 40.08 + 18.998 = 78.08 g
Step 4 : Find grams of CaF₂
Grams of CaF₂ = 
Grams of CaF₂ = 87.45 g
87.45 grams of CaF2 would be needed to produce 1.12 moles of F2.
