The Muriatic acid mixture kills pigweed, lambs quarter weed, range weed, and other small weeds. It kills the weeds’ cellulose chain when applied, resulting in hydrolysis. Handling it requires caution to avoid killing the grass and contaminating the soil. You can use it in diluted amounts to kill unwanted grass and weeds. Muriatic acid kills any plant it touches, including weeds. However, it has its upsides, even in its potency, proper handling can give you neat walkways. An accidental spill can do extensive damage to grass and other vegetation. Undiluted muriatic acid is extremely harmful to plants. It has longevity on grass, and you should clean it up immediately to avoid extensive damage. Careful use can make it an effective weed killer, especially for unwanted growth in hard-to-reach areas. It wreaks havoc on plant roots if the spill seeps into the soil. Muriatic acid will kill grass, weeds, and other smaller vegetation it touches. The acid has many uses in household cleaning, unclogging drains and toilets, but can use it to kill grass and weeds? Muriatic acid is hydrogen chloride in liquid form.