Advertisements
Advertisements
प्रश्न
Explain formula mass with an example.
Advertisements
उत्तर
- The formula mass of a substance is the sum of atomic masses of the atoms present in the formula.
- In substances such as sodium chloride, positive (sodium), and negative (chloride) entities are arranged in a three-dimensional structure in a way that one sodium (Na+) ion is surrounded by six chlorides (Cl–) ions, all at the same distance from it and vice versa. Thus, sodium chloride does not contain discrete molecules as the constituent units.
- Therefore, NaCl is just the formula that is used to represent sodium chloride though it is not a molecule.
- In such compounds, the formula (i.e., NaCl) is used to calculate the formula mass instead of molecular mass.
e.g. Formula mass of sodium chloride = atomic mass of sodium + atomic mass of chlorine
= 23.0 u + 35.5 u
= 58.5 u
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 ______.
Which of the following has the largest number of atoms?
Calculate the molecular mass of the following in u.
CH3COOH
Calculate the molecular mass of the following in u.
C2H5OH
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 u of iodine (I)
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
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
Which one of the following represents 180 g of water?
Which of the following is/are true with respect to carbon-12.
Which one of the following is used as a standard for atomic mass.
Define relative atomic mass.
The reaction between aluminium and ferric oxide can generate temperatures up to 3273 K and is used in welding metals.
(Atomic mass of Al = 27 u Atomic mass of O = 16 u)
\[\ce{2Al + Fe2O3 -> Al2O3 + 2Fe}\]; If, in this process, 324 g of aluminium is allowed to react with 1.12 kg of ferric oxide.
- Calculate the mass of Al2O3 formed.
- How much of the excess reagent is left at the end of the reaction?
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?
Boron has two isotopes 10B and 11B with atomic masses 10 and 11, respectively. If its average atomic mass is 10.81, the abundance of 10B is ____________.
The unit of atomic mass, amu is replaced by u, here u stands for ______.
Which symbol replaces the unit of atomic mass, amu?
0.05 F electricity is passed through CuSO4 solution. Calculate the mass of Cu produced at cathode? (molar mass of Cu = 63.5 g mol-1)
