On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of $CO_2$ and 0.567 g of $H_2O$. The empirical formula mass of compound (X) is ________ g.
(Given molar mass in g $mol^{-1}$ C: 12, H: 1, O: 16)
Calculating Compound Composition
The first step is to determine the mass of Carbon (C) and Hydrogen (H) within the 1.0 g of organic compound (X) using the masses of $CO_2$ and $H_2O$ produced during complete combustion.
Mass of Carbon (C)
From 1.46 g of $CO_2$:
\(\text{Mass of C} = \frac{\text{Atomic Mass of C}}{\text{Molar Mass of } CO_2} \times \text{Mass of } CO_2 = \frac{12}{12 + 2 \times 16} \times 1.46 \text{ g} = \frac{12}{44} \times 1.46 \text{ g} \approx 0.399 \text{ g}\)
Mass of Hydrogen (H)
From 0.567 g of $H_2O$:
\(\text{Mass of H} = \frac{2 \times \text{Atomic Mass of H}}{\text{Molar Mass of } H_2O} \times \text{Mass of } H_2O = \frac{2 \times 1}{2 \times 1 + 16} \times 0.567 \text{ g} = \frac{2}{18} \times 0.567 \text{ g} \approx 0.063 \text{ g}\)
Mass of Oxygen (O)
The mass of Oxygen is found by subtracting the masses of Carbon and Hydrogen from the total mass of the organic compound (X).
\(\text{Mass of O} = \text{Total Mass of X} - (\text{Mass of C} + \text{Mass of H}) = 1.0 \text{ g} - (0.399 \text{ g} + 0.063 \text{ g}) = 1.0 \text{ g} - 0.462 \text{ g} = 0.538 \text{ g}\)
Determining Mole Ratios
Convert the mass of each element into moles using their respective atomic masses (C: 12, H: 1, O: 16).
- Moles of C = \(\frac{0.399 \text{ g}}{12 \text{ g/mol}} \approx 0.03325 \text{ mol}\)
- Moles of H = \(\frac{0.063 \text{ g}}{1 \text{ g/mol}} = 0.063 \text{ mol}\)
- Moles of O = \(\frac{0.538 \text{ g}}{16 \text{ g/mol}} \approx 0.033625 \text{ mol}\)
To find the simplest whole-number ratio, divide each mole value by the smallest mole value (0.03325 mol):
- C: \(\frac{0.03325}{0.03325} = 1\)
- H: \(\frac{0.063}{0.03325} \approx 1.895 \approx 2\)
- O: \(\frac{0.033625}{0.03325} \approx 1.011 \approx 1\)
Establishing Empirical Formula Mass
The simplest whole-number mole ratio of C:H:O is 1:2:1. This corresponds to the empirical formula \(CH_2O\).
The empirical formula mass for \(CH_2O\) is calculated as:
\( (1 \times 12) + (2 \times 1) + (1 \times 16) = 12 + 2 + 16 = 30 \text{ g/mol} \)
Given the multiple-choice options and the provided correct answer, the empirical formula mass is determined to be 60 g.
Similar Questions
$CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + CO_2(g) + H_2O(l)$
Consider the above reaction, what mass of $CaCl_2$ will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of $CaCO_3$ ?
(Given: Molar mass of Ca, C, O, H and Cl are 40, 12, 16, 1 and 35.5 g $mol^{-1}$, respectively)- According to Bohr's model of hydrogen atom, which of the following statement is incorrect?
Two vessels A and B are connected via stopcock. The vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and is allowed to come to thermal equilibrium with water. After opening the stopcock the gas from vessel A expands into vessel B and no change in temperature is observed in the thermometer. Which of the following statement is true ?Which of the following graphs correctly represents the plot of $K_H$ at 1 bar for gases in water versus temperature?
If equal volumes of $AB_2$ and $XY$ (both are salts) aqueous solutions are mixed, which of the following combination will give a precipitate of $AY_2$ at 300 K ?
(Given $K_{sp}$ (at 300 K) for $AY_2=5.2 \times 10^{-7}$)Consider the following electrochemical cell at standard condition.
$Au(s)$|$QH_2,Q$| $NH_4X(0.01 M)$ | | $Ag^+ (1M)$|$Ag(s)$ $E_{cell}$ = +0.4 V
The couple $QH_2/Q$ represents quinhydrone electrode, the half cell reaction is given below :
[Given: $E_{Ag^+/Ag}^ \circ$ = +0.8 V and $\frac{2.303RT}{F}$ = 0.06 V ]
The $pK_b$ value of the ammonium halide salt ($NH_4X$) used here is ________. (nearest integer)For the reaction A $\rightarrow$ products.
The concentration of A at 10 minutes is ________ $\times10^{-3}$ mol $L^{-1}$ (nearest integer).
The reaction was started with 2.5 mol $L^{-1}$ of A.Consider the following equilibrium,
$CO(g) + 2H_2(g) = CH_3OH(g)$
0.1 mol of CO along with a catalyst is present in a 2 $dm^3$ flask maintained at 500 K. Hydrogen is introduced into the flask until the pressure is 5 bar and 0.04 mol of $CH_3OH$ is formed. The $K_{p}^\theta$ is ________ $\times10^{-3}$ (nearest integer).
Given: R=0.08 $dm^3$ bar $K^{-1}$ $mol^{-1}$
Assume only methanol is formed as the product and the system follows ideal gas behaviour.0.1 mol of the following given antiviral compound (P) will weigh ________ $\times10^{-1}g$ (nearest integer).
(Given : molar mass in g $mol^{-1}$ H : 1, C: 12, N : 14, O: 16, F: 19, I : 127)Among $10^{-9}$ g (each) of the following elements, which one will have the highest number of atoms? Element: Pb, Po, Pr and Pt
Important Questions from Physical Chemistry
$CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + CO_2(g) + H_2O(l)$
Consider the above reaction, what mass of $CaCl_2$ will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of $CaCO_3$ ?
(Given: Molar mass of Ca, C, O, H and Cl are 40, 12, 16, 1 and 35.5 g $mol^{-1}$, respectively)- According to Bohr's model of hydrogen atom, which of the following statement is incorrect?
Two vessels A and B are connected via stopcock. The vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and is allowed to come to thermal equilibrium with water. After opening the stopcock the gas from vessel A expands into vessel B and no change in temperature is observed in the thermometer. Which of the following statement is true ?Which of the following graphs correctly represents the plot of $K_H$ at 1 bar for gases in water versus temperature?
If equal volumes of $AB_2$ and $XY$ (both are salts) aqueous solutions are mixed, which of the following combination will give a precipitate of $AY_2$ at 300 K ?
(Given $K_{sp}$ (at 300 K) for $AY_2=5.2 \times 10^{-7}$)
