Calculate the number of grams of the indicated element in the compound.
a) lead in 63.8 g PbO2
b) carbon in 1.664 g (CH3)2CO
Use the ratio of atomic mass to the molecular mass.
For example, to find the number of grams of Na in 20 g of NaOH
atomic mass of Na = 23
molecular mass of NaOH=23+16+1=40
mass of Na in 20 g of NaOH
=20g*(23/40)=11.5g
To calculate the number of grams of an element in a compound, we need to first determine the molar mass of the compound and then use that to find the mass of the desired element.
a) Lead (Pb) in PbO2:
1. Write down the chemical formula of the compound: PbO2
2. Find the molar mass of each element:
- The molar mass of lead (Pb) is 207.2 g/mol.
- The molar mass of oxygen (O) is 16.0 g/mol.
3. Determine the molar mass of PbO2 by multiplying the molar mass of each element by the number of atoms present:
- The molar mass of PbO2 = (207.2 g/mol) + 2*(16.0 g/mol) = 239.2 g/mol.
4. Calculate the mass of lead (Pb) in 63.8 g PbO2 using the molar mass ratio:
- Mass of Pb = (63.8 g PbO2) * (1 mol PbO2 / 239.2 g PbO2) * (207.2 g Pb/mol)
- Mass of Pb = 54.7 g Pb
Therefore, there are 54.7 grams of lead (Pb) in 63.8 grams of PbO2.
b) Carbon (C) in (CH3)2CO:
1. Write down the chemical formula of the compound: (CH3)2CO
2. Find the molar mass of each element:
- The molar mass of carbon (C) is 12.0 g/mol.
- The molar mass of hydrogen (H) is 1.0 g/mol.
- The molar mass of oxygen (O) is 16.0 g/mol.
3. Determine the molar mass of (CH3)2CO by multiplying the molar mass of each element by the number of atoms present:
- The molar mass of (CH3)2CO = 2*(12.0 g/mol) + 6*(1.0 g/mol) + 16.0 g/mol = 58.0 g/mol.
4. Calculate the mass of carbon (C) in 1.664 g (CH3)2CO using the molar mass ratio:
- Mass of C = (1.664 g (CH3)2CO) * (1 mol (CH3)2CO / 58.0 g (CH3)2CO) * (2*(12.0 g C/mol))
- Mass of C = 0.457 g C
Therefore, there are 0.457 grams of carbon (C) in 1.664 grams of (CH3)2CO.
To calculate the number of grams of a specific element in a compound, you need to know the molar mass of that element and the compound's molecular formula.
a) To calculate the number of grams of lead (Pb) in 63.8 g of lead dioxide (PbO2), we need to find the molar mass of PbO2.
First, let's find the molar mass of lead (Pb) by using the periodic table. The atomic mass of lead (Pb) is approximately 207.2 g/mol.
Next, we need to consider that lead dioxide (PbO2) contains two atoms of oxygen (O). The atomic mass of oxygen (O) is approximately 16.00 g/mol.
Now we can calculate the molar mass of PbO2:
Molar mass of PbO2 = (atomic mass of Pb) + 2 * (atomic mass of O)
= 207.2 + 2 * 16.00
= 207.2 + 32.00
= 239.2 g/mol
To calculate the number of grams of lead (Pb) in 63.8 g of PbO2, we can use the following formula:
Grams of Pb = (mass of PbO2) * (molar mass of Pb / molar mass of PbO2)
Substituting the given values:
Grams of Pb = 63.8 * (207.2 / 239.2)
= 55.28 g
Therefore, the number of grams of lead (Pb) in 63.8 g of PbO2 is approximately 55.28 g.
b) To calculate the number of grams of carbon (C) in 1.664 g of acetone [(CH3)2CO], we need to find the molar mass of (CH3)2CO.
Let's break down the molecular formula of acetone:
CH3 represents a methyl (CH3) group, which has a molar mass of approximately 15.03 g/mol.
CO represents a carbonyl (CO) group, which consists of one carbon atom and one oxygen atom. The atomic mass of carbon (C) is approximately 12.01 g/mol, and the atomic mass of oxygen (O) is approximately 16.00 g/mol.
Now let's calculate the molar mass of (CH3)2CO:
Molar mass of (CH3)2CO = (3 * atomic mass of C) + (6 * atomic mass of H) + atomic mass of O
= (3 * 12.01) + (6 * 1.008) + 16.00
= 36.03 + 6.048 + 16.00
= 58.078 g/mol
To calculate the number of grams of carbon (C) in 1.664 g of (CH3)2CO, we can use the following formula:
Grams of C = (mass of (CH3)2CO) * (molar mass of C / molar mass of (CH3)2CO)
Substituting the given values:
Grams of C = 1.664 * (12.01 / 58.078)
= 0.342 g
Therefore, the number of grams of carbon (C) in 1.664 g of (CH3)2CO is approximately 0.342 g.