The original solution used to make the solutions for the standard curve was prepared by dissolving 2.60g of CoCl2 (molar mass 130.g/mol ) in enough water to make 100.mL of solution. What is the molar concentration of the solution?

0.200 M

Explanation:

Step 1: Given data

Step 2: Calculate the moles (n) of CoCl₂ (solute)

We will use the following expression.

n = m/M

n = 2.60 g/(130 g/mol)

n = 0.0200 mol

Step 3: Convert "V" to liters

We will use the conversion factor 1 L = 1000 mL.

100 mL × 1 L/1000 mL = 0.100 L

Step 4: Calculate the molarity of CoCl₂

We will use the definition of molarity.

[CoCl₂] = n/V(L)

[CoCl₂] = 0.0200 mol/0.100 L

[CoCl₂] = 0.200 M

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.