I need to know what volume of liquid phosphoric acid at 85%, H3PO4 with density of 1.685 will replace 5 gr

To determine the volume of liquid phosphoric acid at 85%, H3PO4 with a density of 1.685 that will replace 5 grams, you will need to use the formula:

Volume = Mass / Density

First, you need to convert the mass from grams to the appropriate unit. Since density is given in grams per milliliter (g/mL), it's a good idea to convert the mass to milligrams (mg) for consistency:

5 grams = 5000 milligrams

Next, you can apply the formula to calculate the volume:

Volume = 5000 mg / 1.685 g/mL

Now, you need to convert the volume from milliliters to the appropriate unit. In this case, you want to find the volume in liters, so you need to divide by 1000:

Volume = (5000 mg / 1.685 g/mL) / 1000

Simplifying the expression:

Volume = 2.968 liters (rounded to three decimal places)

Therefore, approximately 2.968 liters of liquid phosphoric acid at 85% concentration H3PO4 with a density of 1.685 will replace 5 grams.