# Solving Concentration Problems: Sodium Cations

• Kyoma
In summary, to calculate the concentration of sodium cations in a solution, divide the moles of Na+ by the total volume of the solution in liters. This is typically expressed in units of molarity (M). Concentration is a general term for the amount of a substance in a given volume or mass, while molarity specifically refers to the concentration of a solute in a given volume of solution. To convert from molarity to parts per million (ppm) for sodium cations, multiply the molarity by the molar mass of Na+ and then by 1,000,000. A standard curve can be used to determine the concentration of Na+ in a solution by comparing its absorbance or emission intensity to a graph
Kyoma

## Homework Statement

15 cm3 of 0.200 mol dm-3 sodium hydroxide solution was made up to 100 cm3 with 0.120 mol dm-3 sodium sulfate solution. Determine the molar concentration of sodium cations in the resultant mixture.

2. The attempt at a solution
Moles of sodium ions in sodium hydroxide = 0.200 x (15/1000) = 0.003 mol
Let volume of sodium sulfate be Vx.
(0.120Vx) x 2 + 0.003 = Total moles of sodium ions

After which, i find it hard to proceed. :(

You started with 15 mL, now you have 100 mL. How many mL were added?

85 mL? But I remember that particles can fit into small spaces, so surely 85 mL is wrong?

## 1. How do I calculate the concentration of sodium cations in a solution?

The concentration of sodium cations (Na+) can be calculated by dividing the moles of Na+ present in the solution by the total volume of the solution in liters. This value is typically expressed in units of molarity (M).

## 2. What is the relationship between concentration and molarity?

Concentration is a general term that refers to the amount of a substance present in a given volume or mass. Molarity specifically refers to the concentration of a solute (in moles) in a given volume of solution (in liters). Mathematically, molarity (M) = moles of solute / liters of solution.

## 3. How do I convert between molarity and ppm for sodium cations?

To convert from molarity to parts per million (ppm) for sodium cations, you will need to know the molar mass of Na+. Multiply the molarity by the molar mass and then convert the result to ppm by multiplying by 1,000,000 (since ppm is a smaller unit than molarity).

## 4. Can I use a standard curve to determine the concentration of sodium cations?

Yes, a standard curve can be used to determine the concentration of sodium cations in a solution. This involves creating a series of solutions with known concentrations of Na+ and measuring the absorbance or emission intensity of each solution. A graph can then be created, and the concentration of an unknown solution can be determined by comparing its absorbance or emission intensity to the standard curve.

## 5. How can I change the concentration of sodium cations in a solution?

The concentration of sodium cations can be changed by adding or removing Na+ ions from the solution. This can be done by diluting the solution with water (which decreases the concentration) or by adding more of the solute (which increases the concentration). Additionally, the concentration of Na+ can be affected by chemical reactions or changes in temperature and pressure.

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