My baking soda's been open for over two months now, maybe even three. It's a pretty big box and it's used partially for all sorts of other fantastic things that baking soda's used for (whites, deodourising etc). I'm thinking I should open a new box but I think my mum would yell at me lol. I've been told that so long as the soda still has a vigorous fizz when you add a little vinegar, it's still good for baking. But I'm not entirely sure.
How long would you keep your soda before replacing it?