Question

Without doing detailed calculations, explain in which of the following materials you would expect to find the greatest mass percent of hydrogen: seawater, the atmosphere, natural gas \(\left(\mathrm{CH}_{4}\right),\) ammonia.

Short answer

Out of the given options, one would expect to find the greatest mass percent of hydrogen in ammonia

Step-by-step solution

Understanding the Elements

Before proceeding, it is important to understand that natural gas is mostly composed of methane, which has a chemical formula of CH4, meaning it contains four hydrogen atoms. Ammonia, on the other hand, has the chemical formula NH3, containing three hydrogen atoms. Seawater contains various salts but the majority of it is H2O, hence with two hydrogen atoms. Atmosphere consists mainly of nitrogen (N2) and oxygen (O2), with only trace amounts of other gasses, so it has very little hydrogen.

Hydrogen in Seawater

Seawater contains a large quantity of water molecules, each containing two hydrogen atoms. However, water only accounts for about 96.5% of seawater and the remainder is mostly salts, which contain no hydrogen.

Hydrogen in the Atmosphere

The atmosphere does contain some hydrogen, but not a lot. This is because hydrogen, being the lightest element, can easily escape Earth's gravitational pull and float out into space. So, the atmosphere is not particularly rich in hydrogen.

Hydrogen in Natural Gas

Natural gas (methane) contains a significant amount of hydrogen. In fact, hydrogen makes up 25% of the atoms in methane. This makes natural gas one of the richer sources of hydrogen among the materials being considered.

Hydrogen in Ammonia

Ammonia has one nitrogen atom and three hydrogen atoms. Considering the atomic masses of nitrogen (14 amu) and hydrogen (1 amu), it can be stated that ammonia consists of 18% nitrogen and 82% hydrogen, making it the richest source of hydrogen among the materials listed here.

Key concepts

Hydrogen Composition

To understand hydrogen composition, it's important to consider how hydrogen fits into the overall structure of a compound. Hydrogen is the simplest and most abundant element in the universe. It appears in many compounds in everyday life, from water to natural gas.

When we discuss hydrogen composition, we're talking about the proportion of hydrogen atoms compared to other elements in a molecule. This is often observed in terms of mass percent.

• In methane (\( ext{CH}_4\)), every molecule has four hydrogen atoms compared to one carbon atom, making hydrogen a significant component.
• Ammonia (\( ext{NH}_3\)) has three hydrogen atoms for each nitrogen atom, giving it a high hydrogen concentration by mass.
• Water (\( ext{H}_2 ext{O}\)) has two hydrogen atoms per oxygen atom, fully representing hydrogen's presence in liquids like seawater.

These compositions highlight the variety and significance of hydrogen across different materials and influence the mass percent of hydrogen in these compounds.

Atomic Structure

Atomic structure is fundamental to understanding why hydrogen is found in certain proportions. An atom consists of a nucleus, containing protons and neutrons, surrounded by electrons. The number of protons in the nucleus defines the element. Hydrogen has one proton and typically one electron, making it the simplest atom.

Due to its simplicity, hydrogen easily forms bonds with other elements. This ability is crucial for creating compounds like water, methane, and ammonia.

• Because it's mostly a carrier of one electron, hydrogen can share or exchange this electron, forming covalent and ionic bonds.
• In methane and ammonia, hydrogen participates in covalent bonding by sharing electrons with carbon and nitrogen, respectively.
• In water, hydrogen forms polar bonds with oxygen, contributing to water's unique properties.

Understanding atomic structure helps explain hydrogen's behavior and its abundance in particular compounds, affecting how we calculate its mass percent in a substance.

Chemical Formulas

Chemical formulas give us a straightforward way to see the composition of a compound. These formulas show which elements are in a compound and how many atoms of each are present. For example, in chemistry, we use formulas to quickly understand the makeup of substances and predict how they will behave.

Each atom in a formula represents part of the molecular weight and affects the mass percent of elements within the compound.

• For methane (\( ext{CH}_4\)), the formula shows that four out of five atoms are hydrogen, indicating a high hydrogen content.
• In ammonia (\( ext{NH}_3\)), three of the four atoms are hydrogen, making up a significant portion of its mass.
• Water (\( ext{H}_2 ext{O}\)) has two hydrogen atoms each molecule, but its high amount in natural water sources raises the mass percent of hydrogen.

Chemical formulas are essential tools in calculating and understanding mass percent, helping us quickly identify the role each element plays in the compound's overall composition.