Relative mass and the mole answer key – The concept of relative mass and the mole plays a crucial role in chemistry, providing a framework for understanding the quantitative aspects of chemical reactions. This guide delves into the definitions, applications, and interrelationship between these fundamental concepts.
Relative mass, also known as atomic mass, quantifies the mass of an atom relative to a standard reference, while the mole serves as the SI unit for measuring the amount of substance. By understanding the relationship between these two concepts, chemists can accurately determine the composition and properties of chemical compounds.
Relative Mass
Relative mass, also known as atomic mass or molecular mass, is a dimensionless quantity that expresses the mass of an atom or molecule relative to the mass of a standard reference. The standard reference is the carbon-12 atom, which is assigned a relative mass of exactly 12.
Relative mass is determined by comparing the mass of an atom or molecule to the mass of the carbon-12 atom. For example, the relative mass of hydrogen is 1.008, which means that a hydrogen atom is 1.008 times heavier than a carbon-12 atom.
The relative mass of oxygen is 16.00, which means that an oxygen atom is 16.00 times heavier than a carbon-12 atom.
Examples of Relative Masses, Relative mass and the mole answer key
- Hydrogen: 1.008
- Carbon: 12.01
- Oxygen: 16.00
- Sodium: 22.99
- Chlorine: 35.45
The Mole: Relative Mass And The Mole Answer Key
The mole is the SI unit of amount of substance. It is defined as the amount of substance that contains as many elementary entities as there are atoms in 0.012 kilograms of carbon-12. The mole is a very large unit, so it is often convenient to use smaller units, such as the millimole (mmol) or the micromole (µmol).
The mole is used to measure the quantity of a substance in a chemical reaction. For example, the balanced chemical equation for the reaction between hydrogen and oxygen to form water is:
“`
H2+ O 2→ 2H 2O
“`
This equation tells us that 2 moles of hydrogen react with 1 mole of oxygen to produce 2 moles of water. The mole is also used to calculate the molar mass of a substance. The molar mass is the mass of one mole of a substance.
For example, the molar mass of water is 18.02 g/mol.
Examples of Using the Mole in Calculations
- To calculate the number of moles of a substance, divide the mass of the substance by its molar mass.
- To calculate the mass of a substance, multiply the number of moles of the substance by its molar mass.
- To calculate the volume of a gas at a given temperature and pressure, use the ideal gas law: PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
Relationship between Relative Mass and the Mole
The relative mass of an atom or molecule is related to the mole by the following equation:
“`relative mass = molar mass / Avogadro’s number“`
where Avogadro’s number is the number of atoms or molecules in one mole of a substance. Avogadro’s number is 6.022 × 10 23mol -1.
This equation can be used to convert between relative mass and molar mass. For example, the relative mass of hydrogen is 1.008, and the molar mass of hydrogen is 1.008 g/mol. This means that there are 6.022 × 10 23hydrogen atoms in one mole of hydrogen.
Table Illustrating the Relationship between Relative Mass and the Mole
| Relative Mass | Molar Mass (g/mol) | Number of Atoms/Molecules |
|---|---|---|
| 1.008 | 1.008 | 6.022 × 1023 |
| 12.01 | 12.01 | 6.022 × 1023 |
| 16.00 | 16.00 | 6.022 × 1023 |
| 22.99 | 22.99 | 6.022 × 1023 |
| 35.45 | 35.45 | 6.022 × 1023 |
Applications of Relative Mass and the Mole
Applications of Relative Mass in Chemistry
- To calculate the molecular mass of a compound
- To determine the empirical formula of a compound
- To calculate the percentage composition of a compound
Applications of the Mole in Chemistry
- To calculate the number of atoms or molecules in a sample
- To calculate the mass of a sample
- To calculate the volume of a gas
Examples of How Relative Mass and the Mole Are Used in Real-World Applications
- To determine the amount of fertilizer to apply to a field
- To calculate the amount of fuel needed to power a car
- To calculate the amount of medication to give to a patient
FAQ Guide
What is the definition of relative mass?
Relative mass is the ratio of the average mass of an atom of an element to 1/12 of the mass of an atom of carbon-12.
How is the mole used to measure quantity?
The mole is used to measure the amount of substance in terms of the number of particles (atoms, molecules, ions, or electrons) present. One mole of a substance contains 6.022 × 10^23 particles.
What is the relationship between relative mass and the mole?
The relative mass of an element is numerically equal to the mass in grams of one mole of that element.
