Question

How many moles of nickel are in \(17.7 \mathrm{~g}\) of \(\mathrm{Ni}\) ?

Short answer

There are approximately 0.301 moles of nickel in 17.7 g of Ni.

Step-by-step solution

Identify the Molar Mass of Nickel

Search the periodic table for the atomic mass of nickel (Ni). The atomic mass of Ni is approximately 58.69 grams per mole (g/mol).

Calculate the Number of Moles

Use the formula for the number of moles: number of moles = mass (g) / molar mass (g/mol). Plug in the given mass of nickel and its molar mass into the formula.

Perform the Calculation

Divide the given mass of the nickel sample by the molar mass of nickel: number of moles = 17.7 g / 58.69 g/mol.

Obtain the Result

Complete the calculation to find out the number of moles in the given mass of nickel.

Key concepts

Molar Mass

Molar mass is a fundamental concept in chemistry that refers to the mass of one mole of a given substance. It is usually expressed in grams per mole (g/mol) and is numerically equivalent to the substance's atomic or molecular mass. The molar mass of an element like nickel can be found by looking at the element's atomic mass listed on the periodic table. When calculating the moles of a substance, knowing the molar mass is crucial because it serves as a conversion factor between the mass of a sample and the amount of substance in moles. In our exercise, the molar mass of nickel was given as 58.69 g/mol, and this information is used to calculate that 17.7 grams of nickel equal approximately 0.30 moles.

It's important for students to remember that the molar mass can vary slightly depending on the isotopic composition of the element they are working with, which is why the periodic table provides an averaged value based on naturally occurring isotopes.

Stoichiometry

Stoichiometry is the area of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It is a vital part of understanding chemistry because it allows us to predict the amounts of substances consumed and produced in a reaction. A stoichiometric calculation often starts with a balanced chemical equation and uses the concept of moles to convert between mass and volume of substances. The exercise of calculating the number of moles of nickel is an example of stoichiometry, as we use the mass of nickel in grams to find out how many moles of nickel we have. This process involves dividing the given mass by the molar mass, both of which must be accurately known to ensure the calculation is correct.

Periodic Table

The periodic table is a tabular arrangement of all known elements, organized by increasing atomic number, electron configuration, and recurring chemical properties. It is an indispensable tool in chemistry as it provides essential information about the elements, including their atomic mass and valency. When you look for the atomic mass of nickel (Ni) or any other element, you find it beneath the element's symbol on the table. The atomic mass listed on the periodic table is an average that accounts for the relative abundance of different isotopes of the element found in nature.

For students learning about moles and molar mass, the periodic table is the go-to reference to find the data needed for calculations. In our case, to calculate the moles of nickel, you would look for the atomic mass of Ni on the periodic table, which is 58.69, and use this number as the molar mass in your calculation.

Atomic Mass

Atomic mass, often referred to as atomic weight, is the average mass of atoms of an element, measured in atomic mass units (amu). Each element has its own unique atomic mass, which takes into account the distribution of isotopes and their respective masses. The simple definition is that the atomic mass is the mass of one mole of atoms of an element. While the concept may seem straightforward, it's important to understand that the atomic mass on the periodic table is an average value because naturally occurring elements usually consist of a mix of isotopes, each having its own mass.

In practice, when performing calculations for the moles of a single element like nickel, you use the atomic mass given on the periodic table as the molar mass, as was done in our exercise. By doing this, we are able to convert grams to moles, connecting the tangible mass of a sample to the abstract number of particles it contains.