We actually did almost this exact shot for a karate instructor's portfolio- I don't have rights to share it with you on the internet as I wasn't the photog, and it was used in a private usage.
What we did: It's a little hazy - as we tried a LOT of different things to get this to work, and I don't recall clearly which was the "Winner"...
We set up a small cloth beanbag-like bag that had the corners cut off and small slits cut in the sides and adhered it to the surface that was being struck. I think we used an old sock that was cut off and sewn mostly shut with some holes cut in it if I'm remembering correctly - maybe even a bit of nylon stocking??? The bag was filled loosely with chalk - I'll be honest, I think we ended up substituting corn starch for the chalk in order to achieve the "explosive" effect we were after. The key was loose packing the chalk substance as it would then billow out of the openings when the impact occurred. The idea behind using the bag was to have a LOT more chalk than what would simply stick to a surface.
I bet you could use something as simple as a small paper envelope to achieve the same thing...
We got the idea from an old college prank we'd play on each other... put a few folds in a manilla envelope length-wise, puff the envelope up using the folds as reinforcement, add some glitter to the opening, slide the opening under a closed dorm-room door and then stomp on it to create a magically festive atmosphere inside the room.
Glitter: The herpes of craft supplies. Once you get it, you can't get rid of it.