Why densities of pure and salt water are different

This results in an increase in the overall volume of the saltwater compared to pure water, causing a decrease in density. This can be mathematically shown by the lower density of seawater (1020-1030 kg/m3) compared to the density of pure water (1000 kg/m3). In summary, when salt is added to water, the ions of the salt change the density of the water by increasing its volume and decreasing its overall density.
  • #1
yjk91
75
0
Density = mass/volume (D=m/v), explain the difference in density of pure & salt water in words and using a mathematically based example
 
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  • #2
The ions of the salt fill space within the liquid. Not sure about any equations to help with this.
 
  • #3
density of pure water and impure water are different... as you said, density = mass/volume.

what do you think will happen to the mass and volume when salt is added to the water?!
 
  • #5
symbolipoint said:
The ions of the salt fill space within the liquid. Not sure about any equations to help with this.

Not exactly, ions are ordering water molecules, changing how densely they are packed.
 

FAQ: Why densities of pure and salt water are different

1. Why is the density of salt water higher than pure water?

The density of salt water is higher than pure water because salt water contains dissolved ions, such as sodium and chloride, which increase the mass of the water without significantly changing its volume. This results in a higher overall density compared to pure water.

2. How does temperature affect the density of salt water?

Temperature affects the density of salt water in the same way it affects the density of pure water. As the temperature of salt water decreases, the density increases. This is because the molecules of water become more tightly packed together as they lose energy and slow down. The addition of salt does not significantly change this relationship.

3. Does the concentration of salt affect the density of salt water?

Yes, the concentration of salt does affect the density of salt water. As the concentration of salt increases, the density of the water also increases. This is because there are more ions present in the water, increasing the overall mass without significantly changing the volume.

4. Why does the density of salt water vary in different bodies of water?

The density of salt water can vary in different bodies of water due to differences in temperature and salinity. For example, water in warmer, more tropical regions tends to have a higher salt content and therefore a higher density compared to colder, polar regions. Additionally, factors such as currents and mixing of different water masses can also impact the density of salt water.

5. Can the density of salt water be measured without testing the salinity?

Yes, the density of salt water can be measured without directly testing the salinity. This can be done using a device called a hydrometer, which measures the density of a liquid by floating in it. The more dense the liquid, the higher the hydrometer will float. This method can be used to indirectly determine the salinity of the water based on its density.

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