Question

Danny weighs 4.9699 g of NaCl on a balance in a chemistry lab. how many moles of this compound did he weigh?

Anita prepares a 0.02000L solution of NaCl from the mass of NaCl that danny weighed in the previous question. what is the concentration (molarity) of the newly prepared solution?​​

a) 0.1 moles
b) 0.2 moles
c) 0.3 moles
d) 0.4 moles

Answer 1

Danny weighed 4.9699 g of NaCl, which equals 0.072 moles when divided by NaCl's molar mass of 58.44 g/mol. Anita's 0.02000L solution made from this mass has a molarity of 3.6 M.

Step-by-step explanation:

Danny weighed 4.9699 grams of NaCl. To find the number of moles of NaCl, we use the molar mass of NaCl (58.44 g/mol) and divide the mass of the NaCl Danny weighed by this molar mass. 0.072 moles is the result of this calculation.

Next, Anita prepares a 0.02000 L (or 20.00 mL) solution using the mass of NaCl Danny weighed. The concentration (molarity) of the solution is calculated by dividing the number of moles by the volume in liters. Thus, the molarity of the solution is 0.072 moles divided by 0.02 liters, which equals 3.6 M, indicating the solution is very concentrated.