The question above was in a school chemistry textbook. The answer (IIRC) was that due to osmotic effects, red blood cells absorb water, which makes them burst open. This releases some red colored substance that was contained in the cells (aimocyte sp?) that dyes the water red.
My (probably silly) question is this: What if red blood cells didn’t burst open? Wouldn’t blood still dye the water? Aren’t blood cells water soluble?
Blood cells water soluble? They’ve got a great deal of water in them already, and the plasma that carries them is mostly water, plus handy proteins and hormones.
The red-coloured substance in red blood cells is haemoglobin, which owes its red colouring to iron in a certain form, haem.
However, the red blood cells wouldn’t have to dissolve to dye water red. They could merely spread out and remain suspended in the water, which would range from red through pinkish to completely clear, depending on the amount of blood and the amount of water.
The textbook is stupid. I’m sure that an isotonic liquid (like saline solution) that wouldn’t cause the red cells to burst would still turn color. They’re tiny red things. If they spread through the water, they’ll turn it red, whether or not they lyse.