And then finally the last type. We just said strong acid in week base. So let's reverse it. Weak acid and strong base. So example here we could have one point. Let's do different. Number 250 Mueller HF. Now that's a weak acid and 1.0 Mueller N a O h. Okay, so now are weak. Acid is definitely larger, an amount so again here we need the week species higher in amount. So this would be a buffer. Got to remember that. So if we go back, first way is to mix weak acid and contacted base here. They could be equal to or differ from each other. But the good buffers are within the range of 10 to 1 in the next to the week. Species has to be higher than the strong species. Otherwise, it won't be a buffer. You have to remember all three cases because you'll be tested on them. And if you don't know which is which, you won't be able to get the correct answer. So just remember we cast the contact base that could be equal. It could be different asl, long as it's within the range of 10 to 1. It's a good buffer. If it's outside that range, it's a bad buffer. Case two and three the week Species have to be higher than the strong species. The strong species cannot be equal to or greater. If it is, the buffer gets destroyed. Remember these principles and the help guide you to see if you have a buffer or not.