A compound composed of only carbon and hydrogen is 7.743% hydrogen by mass. Propose a Lewis structure for the compound.

Verified step by step guidance

1. Step 1: The problem states that the compound is composed of only carbon and hydrogen. The atomic mass of carbon (C) is approximately 12.01 g/mol and the atomic mass of hydrogen (H) is approximately 1.01 g/mol. The percentage composition by mass of an element in a compound is given by the formula: (mass of element in 1 mol of compound / molar mass of compound) * 100%. Given that the compound is 7.743% hydrogen by mass, we can use this formula to find the ratio of the masses of carbon and hydrogen in the compound.
2. Step 2: Assume that we have 100 g of the compound. This means that we have 7.743 g of hydrogen and 92.257 g of carbon. To find the number of moles of each element, we divide the mass of each element by its atomic mass. This gives us the number of moles of hydrogen and carbon in the compound.
3. Step 3: To find the simplest whole number ratio of the elements in the compound, divide the number of moles of each element by the smallest number of moles calculated in step 2. This gives us the empirical formula of the compound.
4. Step 4: The empirical formula represents the simplest whole number ratio of the elements in the compound, but not necessarily the actual number of atoms of each element in a molecule of the compound. To propose a Lewis structure, we need to know the molecular formula, which gives the actual number of atoms of each element in a molecule of the compound. However, without additional information, we can only propose a Lewis structure based on the empirical formula.
5. Step 5: Draw the Lewis structure based on the empirical formula. Carbon typically forms four bonds and hydrogen forms one bond in stable compounds. Arrange the carbon atoms in a chain or ring and attach the hydrogen atoms to the carbon atoms such that each carbon atom forms four bonds.

Key Concepts

Empirical Formula

The empirical formula represents the simplest whole-number ratio of elements in a compound. In this case, knowing that the compound is 7.743% hydrogen by mass allows us to determine the ratio of hydrogen to carbon, which is essential for proposing a Lewis structure.

Lewis Structure

A Lewis structure is a diagram that represents the bonding between atoms in a molecule and the lone pairs of electrons. It helps visualize how atoms are connected and the distribution of electrons, which is crucial for understanding the compound's chemical behavior and reactivity.

Molecular Weight and Composition

Understanding the molecular weight and composition of a compound is vital for determining its molecular formula. By calculating the total mass of carbon and hydrogen based on the given percentage, we can derive the molecular formula, which informs the Lewis structure and the overall structure of the compound.