Advertisements
Advertisements
प्रश्न
Solve problem:
Calculate the number of moles of magnesium oxide, MgO in
- 80 g, and
- 10 g of the compound.
(Average atomic masses of Mg = 24 and O = 16)
Advertisements
उत्तर
Given: i. Mass of MgO = 80 g
ii. Mass of MgO = 10 g
To find: Number of moles of MgO
Formulae: Number of moles (n) = `"Mass of a substance"/"Molar mass of a substance"`
Calculation: i. Molecular mass of MgO = (1 × Average atomic mass of Mg) + (1 × Average atomic mass of O)
= (1 × 24 u) + (1 × 16 u)
= 40 u
∴ Molar mass of MgO = 40 g mol−1
Mass of MgO = 80 g
Number of moles (n) = `"Mass of a substance"/"Molar mass of a substance"`
= `(80 "g")/(40 "g mol"^-1)`
= 2 mol
ii. Mass of MgO = 10 g, Molar mass of MgO = 40 g mol–1
Number of moles (n) = `"Mass of a substance"/"Molar mass of a substance"`
= `(10 "g")/(40 "g mol"^-1)`
= 0.25 mol
- The number of moles in 80 g of magnesium oxide, MgO = 2 mol
- The number of moles in 10 g of magnesium oxide, MgO = 0.25 mol
APPEARS IN
संबंधित प्रश्न
Choose the correct option.
Which of the following has maximum number of molecules?
The number of molecules in 22.4 cm3 of nitrogen gas at STP is ______.
Calculate the molecular mass of the following in u.
NH3
Calculate the molecular mass of the following in u.
CH3COOH
What is the ratio of molecules in 1 mole of NH3 and 1 mole of HNO3?
Solve problem:
Calculate the number of an atom of the following (Given: Atomic mass of I = 127 u).
254 g of iodine (I)
Solve problem:
Arjun purchased 250 g of glucose (C6H12O6) for Rs 40. Find the cost of glucose per mole.
Solve problem:
Calculate the number of atoms of the following. (Average atomic mass : N = 14 u, S = 32 u)
0.4 mole of nitrogen
Solve problem:
Calculate the number of atoms of the following. (Average atomic mass : N = 14 u, S = 32 u)
1.6 g of sulfur
Calculate the number of atoms of hydrogen present in 5.6 g of urea, \[\ce{(NH2)2CO}\]. Also calculate the number of atoms of N, C, and O.
Solve problem:
Calculate the mass of sulfur dioxide produced by burning 16 g of sulfur in excess of oxygen in the contact process. (Average atomic mass : S = 32 u, O = 16 u)
An element X has the following isotopic composition 200X = 90%, 199X = 8% and 202X = 2%. The weighted average atomic mass of the element X is closest to
Two 22.4 litre containers A and B contains 8 g of O2 and 8 g of SO2 respectively at 273 K and 1 atm pressure, then
Calculate the average atomic mass of naturally occurring magnesium using the following data.
| Isotope | Isotopic atomic mass | Abundance (%) |
| Mg24 | 23.99 | 78.99 |
| Mg25 | 24.99 | 10.00 |
| Mg26 | 25.98 | 11.01 |
An element has a bee structure with cell edge of 288 pm. The density of element is 7.2 g cm-3. What is the atomic mass of an element?
How many moles of ammonia are present in 5.6 cm3 of ammonia gas at STP?
What is the average mass of an element if it has two isotopes, one of mass 6.015 u with 8.24 % and other of mass 7.016 u with 91.26% respectively?
One amu is equal to ________.
Calculate mass of 3.01 × 1024 atoms of an element having atomic mass 21.13.
A 100 g of sample of haemoglobin on analysis was found to contain 0.34% Fe by mass. If each haemoglobin molecule has four Fe2+ ions, the molecular mass of haemoglobin is: (Fe = 56 amu)
It is found that in 11.2 L at 0°C and 1 atm, of any gaseous compound of 'X', there is never less than 15.5 gm of 'X'. It is also found that 11.2 L of vapours of 'X' at 0°C and 1 atm, weighs 62 gm. The atomicity of 'X' is ______.
Which symbol replaces the unit of atomic mass, amu?
