You can solve this by dividing the mass by the molar mass. The molar mass of CuF2 is about 101.5 g/mol. Therefore there are 100.0/101.5 = 0.985 mol.
They should report the density as 1.11 g/L
.
Density = mass/volume = 2.260g/2.04 mL
My calculator says the density <em>1.107 843 137 g/mL</em>
However, the answer can have <em>no more</em> significant figures than are in the number with the <em>fewest </em>significant figures.
The volume measurement has only three significant figures, so we must round off the density to three significant figures.
We drop all the digits after the zero.
The digit to be dropped is 7, so we <em>round up </em>the last significant figure of the answer.
1.10<u>7 843 137</u> → 1.11
Answer:
10.10
Explanation:
Step 1: Write the basic dissociation reaction for pyridine
C₅H₅N(aq) + H₂O(l) ⇌ C₅H₅NH⁺(aq) + OH⁻(aq) Kb = 1.9 × 10⁻⁹
Step 2: Calculate [OH⁻]
For a weak base, we will use the following expression.
[OH⁻] = √(Cb × Kb) = √(9.2 × 1.9 × 10⁻⁹) = 1.3 × 10⁻⁴ M
Step 3: Calculate pOH
We will use the definition of pOH.
pOH = -log [OH⁻] = -log 1.3 × 10⁻⁴ = 3.9
Step 4: Calculate pH
We will use the following expression.
pH = 14 - pOH = 14 - 3.9 = 10.10
Answer : The mass of arsenic present in 5.0 g of orpiment is, 1.5 grams.
Explanation : Given,
Mass of orpiment = 5.0 g
As we know that the molar mass of 
is, 246.02 g/mol and the molar mass of As is, 75 g/mol.
As per the question, we conclude that:
As, 246.02 g of contains mass of arsenic = 75 g
So, 5.0 g of contains mass of arsenic = 
Thus, the mass of arsenic present in 5.0 g of orpiment is, 1.5 grams.
