$(a)$ Define polyatomic ions. Write an example.
$(b)$ Calculate the formula unit mass of $CaCO_{3}$. (Atomic mass of $C = 12 \ u, Ca = 40 \ u, O = 16 \ u$)
$(c)$ Calculate the molecular mass of the following:
$(i)$ $HNO_{3}$
$(ii)$ $CH_{3}COOH$
(Atomic mass of $H = 1 \ u, N = 14 \ u, O = 16 \ u, C = 12 \ u$)
$(b)$ Calculate the formula unit mass of $CaCO_{3}$. (Atomic mass of $C = 12 \ u, Ca = 40 \ u, O = 16 \ u$)
$(c)$ Calculate the molecular mass of the following:
$(i)$ $HNO_{3}$
$(ii)$ $CH_{3}COOH$
(Atomic mass of $H = 1 \ u, N = 14 \ u, O = 16 \ u, C = 12 \ u$)
(N/A) group of atoms carrying a charge is known as a polyatomic ion.
Example: $NH_{4}^{+}, PO_{4}^{3-}, SO_{4}^{2-}$.
$(b)$ Formula unit mass of $CaCO_{3} = (1 \times \text{Atomic mass of } Ca) + (1 \times \text{Atomic mass of } C) + (3 \times \text{Atomic mass of } O)$
$= 40 \ u + 12 \ u + (3 \times 16 \ u) = 40 + 12 + 48 = 100 \ u$.
$(c)$ $(i)$ Molecular mass of $HNO_{3} = (1 \times \text{Atomic mass of } H) + (1 \times \text{Atomic mass of } N) + (3 \times \text{Atomic mass of } O)$
$= 1 \ u + 14 \ u + (3 \times 16 \ u) = 1 + 14 + 48 = 63 \ u$.
$(ii)$ Molecular mass of $CH_{3}COOH = (2 \times \text{Atomic mass of } C) + (4 \times \text{Atomic mass of } H) + (2 \times \text{Atomic mass of } O)$
$= (2 \times 12 \ u) + (4 \times 1 \ u) + (2 \times 16 \ u) = 24 + 4 + 32 = 60 \ u$.
Example: $NH_{4}^{+}, PO_{4}^{3-}, SO_{4}^{2-}$.
$(b)$ Formula unit mass of $CaCO_{3} = (1 \times \text{Atomic mass of } Ca) + (1 \times \text{Atomic mass of } C) + (3 \times \text{Atomic mass of } O)$
$= 40 \ u + 12 \ u + (3 \times 16 \ u) = 40 + 12 + 48 = 100 \ u$.
$(c)$ $(i)$ Molecular mass of $HNO_{3} = (1 \times \text{Atomic mass of } H) + (1 \times \text{Atomic mass of } N) + (3 \times \text{Atomic mass of } O)$
$= 1 \ u + 14 \ u + (3 \times 16 \ u) = 1 + 14 + 48 = 63 \ u$.
$(ii)$ Molecular mass of $CH_{3}COOH = (2 \times \text{Atomic mass of } C) + (4 \times \text{Atomic mass of } H) + (2 \times \text{Atomic mass of } O)$
$= (2 \times 12 \ u) + (4 \times 1 \ u) + (2 \times 16 \ u) = 24 + 4 + 32 = 60 \ u$.
Explore More
Similar Questions
$(a)$ Calculate the percentage of oxygen in $H_{2}O_{2}$.
$(b)$ Calculate the number of moles in $56 \, g$ of nitrogen gas $(N_{2})$.
$(c)$ Calculate the mass of $0.50$ moles of $Ca$ atoms.
$(d)$ Find out the number of particles in:
$(i)$ $5$ moles of methane gas $(CH_{4})$
$(ii)$ $92 \, g$ of sodium $(Na)$
(Atomic masses: $H=1, O=16, N=14, Ca=40, Na=23$)
$(b)$ Calculate the number of moles in $56 \, g$ of nitrogen gas $(N_{2})$.
$(c)$ Calculate the mass of $0.50$ moles of $Ca$ atoms.
$(d)$ Find out the number of particles in:
$(i)$ $5$ moles of methane gas $(CH_{4})$
$(ii)$ $92 \, g$ of sodium $(Na)$
(Atomic masses: $H=1, O=16, N=14, Ca=40, Na=23$)
Medium
View SolutionFill in the missing data in the Table.
Species property $H_2O$ $CO_2$ $Na$ atom $MgCl_2$ No. of moles $2$ - - $0.5$ No. of particles - $3.011 \times 10^{23}$ - - Mass $36 \, g$ - $115 \, g$ -
| Species property | $H_2O$ | $CO_2$ | $Na$ atom | $MgCl_2$ |
| No. of moles | $2$ | - | - | $0.5$ |
| No. of particles | - | $3.011 \times 10^{23}$ | - | - |
| Mass | $36 \, g$ | - | $115 \, g$ | - |
Medium
View SolutionComplete the following crossword puzzle by using the names of the chemical elements based on the data provided in the table.
Across Down $2$. The element used by Rutherford during his $\alpha$-scattering experiment. $1$. $A$ white lustrous metal used for making ornaments and which tends to get tarnished black in the presence of moist air. $3$. An element which forms rust on exposure to moist air. $4$. Both brass and bronze are alloys of this element. $5$. $A$ very reactive non-metal stored under water. $6$. The metal which exists in the liquid state at room temperature. $7$. Zinc metal when treated with dilute hydrochloric acid produces a gas of this element which when tested with a burning splinter produces a pop sound. $8$. An element with the symbol $Pb$.
| Across | Down |
|---|---|
| $2$. The element used by Rutherford during his $\alpha$-scattering experiment. | $1$. $A$ white lustrous metal used for making ornaments and which tends to get tarnished black in the presence of moist air. |
| $3$. An element which forms rust on exposure to moist air. | $4$. Both brass and bronze are alloys of this element. |
| $5$. $A$ very reactive non-metal stored under water. | $6$. The metal which exists in the liquid state at room temperature. |
| $7$. Zinc metal when treated with dilute hydrochloric acid produces a gas of this element which when tested with a burning splinter produces a pop sound. | $8$. An element with the symbol $Pb$. |
$(a)$ What do the following formulae stand for:
$(i)$ $2O$
$(ii)$ $O_{2}$
$(iii)$ $O_{3}$
$(iv)$ $H_{2}O$
$(b)$ Give the chemical formulae of the following compounds:
$(i)$ Potassium carbonate
$(ii)$ Calcium chloride
$(c)$ Calculate the formula unit mass of $Al_{2}(SO_{4})_{3}$.
(Given atomic mass of $Al = 27 \, u, S = 32 \, u, O = 16 \, u$)
$(i)$ $2O$
$(ii)$ $O_{2}$
$(iii)$ $O_{3}$
$(iv)$ $H_{2}O$
$(b)$ Give the chemical formulae of the following compounds:
$(i)$ Potassium carbonate
$(ii)$ Calcium chloride
$(c)$ Calculate the formula unit mass of $Al_{2}(SO_{4})_{3}$.
(Given atomic mass of $Al = 27 \, u, S = 32 \, u, O = 16 \, u$)
Medium
View SolutionState the postulate of Dalton's atomic theory which led to the law of conservation of mass. Calculate the molecular mass of water.
Easy
View SolutionVedclass Products
For Students
Vedclass Test Series
Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.
Start Free TrialFor Teachers
Exam Paper Generator
Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.
Try FreeFor Institutes
Online Exam Module
Live online exams with unlimited students, 360° analytics & white-label branding.
See Demo