Some Basic Concepts of Chemistry

Calculate the mass of 10 moles of Hydrogen gas ($H_{2}$).

What is the molar mass of Magnesium Oxide ($MgO$)? (Atomic masses: $Mg=24, O=16$)

How many molecules are present in 2.2 grams of $CO_{2}$? (Molar mass of $CO_{2} = 44$ g/mol)

Calculate the mass of $0.1$ moles of Nitrogen gas ($N_{2}$). (Atomic mass: $N = 14$)

How many moles of Hydrogen atoms are contained in $1$ mole of Glucose ($C_{6}H_{12}O_{6}$)?

Calculate the total number of atoms in $4$ g of Hydrogen gas ($H_{2}$). (Atomic mass $H=1$)

The vapor density of a gas is $32$. What is its molar mass?

Two oxides of a metal contain $27.6\%$ and $30.0\%$ of oxygen respectively. If the formula of the first oxide is $M_{3}O_{4}$, find that of the second.

If $4.4$ g of an unknown gas occupies $2.24$ L at STP, the gas could be:

What is the number of moles of solute in $500$ mL of $0.1$ M $K_{2}Cr_{2}O_{7}$ solution?

What is the molar mass of Nitric Acid ($HNO_{3}$)? (Atomic masses: $H = 1, N = 14, O = 16$)

Which of the following has the same empirical formula as Ethyne ($C_{2}H_{2}$)?

In the reaction $Zn + 2HCl \rightarrow ZnCl_{2} + H_{2}$, what volume of $H_{2}$ at STP is produced from 1 mole of Zinc?

What is the mass of 10 moles of Hydrogen gas ($H_{2}$)?

One mole of an ideal gas at $273\,K$ and $1\,atm$ pressure (STP) occupies a volume of:

How many oxygen atoms are there in 88 g of $CO_{2}$?

What is the percentage yield of a reaction if the theoretical yield is 25 g but only 20 g of product is actually obtained?

For the reaction $MnO_{2} + 4HCl \rightarrow MnCl_{2} + 2H_{2}O + Cl_{2}$, if $5 \text{ g}$ of $MnO_{2}$ is reacted with $4.38 \text{ g}$ of $HCl$, what is the mass of $Cl_{2}$ produced? (Mn=55, Cl=35.5, O=16)

$1.5 \text{ g}$ of an impure sample of sodium carbonate was dissolved in water and made up to $250 \text{ mL}$. $25 \text{ mL}$ of this solution required $20 \text{ mL}$ of $0.1 \text{ N } HCl$ for neutralization. Calculate the percentage purity of the sodium carbonate. (Eq. mass = 53)

What is the mass of $CaCO_{3}$ required to react completely with $25 \text{ mL}$ of $0.75 \text{ M } HCl$?

Find the molecular formula of a substance with empirical formula $CH$ and a molecular mass of 78.

Diborane has the molecular formula $B_2H_6$. What is its empirical formula?

What is the empirical formula of the sulfur molecule $S_8$?

Ethanoic acid has the formula $C_2H_4O_2$. What is its empirical formula?

Which of the following pairs of compounds have the same empirical formula?

If the molecular formula of a compound is $C_6H_{12}O_6$, what is its empirical formula weight in amu? ($C=12, H=1, O=16$)

Determine the empirical formula of a chromium oxide that contains $68.4\%$ Chromium and $31.6\%$ Oxygen. ($Cr=52, O=16$)

A $1.5\,g$ sample of a hydrocarbon on combustion yields $4.4\,g$ of $CO_2$. If the vapor density of the hydrocarbon is $15$, what is its molecular formula?

A compound has $C=26.7\%, H=2.2\%, O=71.1\%$. Its molecular mass is $90$. What is the molecular formula?

The percentage of $Se$ in peroxidase anhydrous enzyme is $0.5\%$ by weight. If the atomic weight of $Se$ is $78.4$, what is the minimum molecular weight of the enzyme?

Avogadro's Law provides a relationship between:

Which law was given by Richter in 1792?

According to the Law of Conservation of Mass, in the reaction: $2H_{2} + O_{2} \rightarrow 2H_{2}O$, if $4$ g of $H_{2}$ reacts with $32$ g of $O_{2}$, the mass of $H_{2}O$ produced is:

The fact that $H_{2}S$ contains $94.11\%$ sulfur and $SO_{2}$ contains $50\%$ sulfur can be used along with $H_{2}O$ to demonstrate:

A reaction vessel contains $10$ L of Nitrogen gas and $24$ L of Hydrogen gas. They react to form Ammonia ($NH_3$) gas according to the equation: $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$. Assuming the temperature and pressure remain constant throughout the process, what is the final volume of the gaseous mixture in the vessel after the reaction is complete?

In $NH_3$, $N$ and $H$ are in the ratio $14:3$ by mass. In $N_2H_4$, $N$ and $H$ are in the ratio $14:6$ (or $7:3$) by mass. This comparison of $14:3$ and $14:6$ demonstrates:

Which law was used by Dalton as a basis for his atomic theory to explain the quantitative nature of chemical reactions?

In a study of the Law of Reciprocal Proportions, three elements $P$, $Q$, and $R$ were combined to form different compounds. In compound $PQ$, the mass percentage of $P$ is $75\%$, while in compound $QR$, the mass percentage of $Q$ is $20\%$. If elements $P$ and $R$ combine to form a third compound $PR$, calculate the mass of $P$ that will react with exactly $32.0\text{ g}$ of $R$, assuming the weights follow the simple ratio established by their combinations with $Q$.

$1.0\text{ L}$ of Oxygen and $2.0\text{ L}$ of Hydrogen are mixed and ignited. What is the volume of the resulting gas mixture at $110^\circ C$ and $1\text{ atm}$?

Which law was a direct consequence of Dalton's Atomic Theory but was actually formulated before it?