Integers Rules ADDITION When we ADD a POSITIVE number we move UP the number line. e.g. (-3) + 7 = 4 When we ADD a NEGATIVE number we move DOWN the number line. e.g. 2 + (-8) = -6 SUBTRACTION When we SUBTRACT a POSITIVE number we move DOWN the number line.ntegers Rules ADDITION When we ADD a POSITIVE number we move UP the number line. e.g. (-3) + 7 = 4 When we ADD a NEGATIVE number we move DOWN the number line. e.g. 2 + (-8) = -6 SUBTRACTION When we SUBTRACT a POSITIVE number we move DOWN the number line.
Commercially sold distilled white vinegar in the US is acetic acid in water, at a concentration of 5% by mass for a pH of around 2.4â2.6. If you add water to it, the pH will go up. If you distill it (vinegar is more volatile than water) the resulting distillate will have a lower pH.
When vinegar reaches soil level it is quickly neutralized so that it is no longer acidic. The acetic acid in vinegar is converted to harmless acetate salts which have little effect on the weed. The weed just regrows and in a week or so, the weed is back. Vinegar is not a natural weed killer. Vinegar is about 5% acetic acid, the rest being water. Pickling vinegar is about 7% acetic acid, but even this is not strong enough to kill weeds. A higher concentration of acetic acid will kill some plants, but you need to use at least 20% acetic acid.