Zinc (Zn) always has a +2 charge. It is one of the exceptions.
Unit of M is also mole/L, where mole is the moles of solute and L is the volume of the solution. The latter is given: 158 mL or 0.158 L. So we need to find out the moles of NH4Br.
Moles of NH4Br = Mass of NH4Br/molar mass of NH4Br = 17.0g/(14+1*4+79.9)g/mol = 0.1736 mole.
So, the molarity of the solution = 0.1736mole/0.158L = 1.10 mole/L = 1.10 M
Molarity (concentration) can be calculated by the equation:
Concentration = moles / volume in L = 0.54 mol / 0.6 L = 0.9 M
Hope this helps!
Answer:
A pure substance has a definite chemical composition
