No, salt water melts ice faster than fresh water.
How Salt Affects Ice Melting
Adding salt to water lowers its freezing point. This means that the water needs to be colder than 0°C (32°F) to freeze. Since the salt water is already at a temperature above its freezing point (assuming it's above 0°C), it can absorb more heat from the ice, causing the ice to melt more quickly.
- Experimental Evidence: Repeated tests demonstrated that ice cubes melted twice as fast in saltwater (7 minutes) compared to freshwater (14 minutes). This clearly shows the accelerating effect of salt on the melting process.
The Science Behind It
The process involves several factors:
- Lowered Freezing Point: Salt dissolves in water, disrupting the water molecules' ability to form a crystalline structure (ice). This lowers the freezing point, allowing the water to remain liquid at temperatures below 0°C.
- Increased Heat Absorption: The warmer salt water readily absorbs heat from the surrounding environment and the ice itself, speeding up the melting process.
- Ionic Conductivity: The dissolved salt ions in the water increase its electrical conductivity which also plays a small part in accelerating the melting process.
Practical Implications
Understanding this phenomenon is crucial in various applications, including:
- De-icing roads and pavements: Salt is used to melt ice on roads and sidewalks because of its ability to lower the freezing point of water.
- Food preservation: Salt is sometimes used in food preservation techniques, but primarily by inhibiting microbial growth and not solely due to its ice-melting properties.
