Question

How many molecules are in 35 g of NBr2? Round your answer to 2 decimal places.

a) 2.46 x 10^23 molecules
b) 3.95 x 10^23 molecules
c) 1.22 x 10^23 molecules
d) 5.78 x 10^23 molecules

Answer 1

To find the number of molecules in 35 g of NBr2, calculate the number of moles using the molar mass and then convert moles to molecules using Avogadro's number.

Step-by-step explanation:

To find the number of molecules in 35 g of NBr2, we need to use the concept of moles and Avogadro's number. First, we calculate the number of moles of NBr2 using its molar mass. The molar mass of NBr2 is 187.7 g/mol (14.0 g/mol for N and 2x79.9 g/mol for Br).

Number of moles = mass / molar mass = 35 g / 187.7 g/mol = 0.1866 mol.

Next, we use Avogadro's number (6.02 x 1023 molecules/mol) to convert moles to molecules. Number of molecules = number of moles x Avogadro's number = 0.1866 mol x 6.02 x 1023 molecules/mol = 1.12 x 1023 molecules.

Rounding to 2 decimal places, the correct answer is option a) 1.12 x 1023 molecules.