Question

A sample of seaweed contains two liters of water and has 100 grams of salt dissolved in its cells. The seaweed is placed in a bucket with 4 liters of water and 300 grams of dissolved salt. What will occur when the system reaches equilibrium?

Answer 1

The seaweed will lose 0.5 liters of water.

Step-by-step explanation:

Answer 2

The seaweed will lose 0.5 L of water.

Step-by-step explanation:

We can calculate the concentration of salt dissolvied in the sample of seaweed:

• 100 g / 2 L = 50 g/L

We can also calculate the salt concentration in the bucket:

• 300 g / 4 L = 75 g/L

Once the seaweed is placed in the bucket, it will act as a semipermeable membrane, allowing an osmosis process, in which water will move from the seaweed (the region with lower concentration) to the bucket (the region with higher concentration). So the seaweed will lose water until the salt concentration the seaweed and the bucket is the same.

It's possible to calculate how much water is transfered:

• At equilibrium, the volume of water in the seaweed is 2L - x; and the volume in the bucket is 4L + x.

Because the concentrations are equal:

• 100 g / (2L-x) = 300 g / (4L+x)

Now we solve for x:

• 100 * (4+x) = 300 * (2-x)

• 400 + 100x = 600 - 300x

• 400x=200

• x=0.5 L