5. How many grams of KNO3 will be required to prepare 800 mL of 1.40 M KNO3?

113.2

To calculate the number of grams of KNO3 required, you need to use the concentration and volume provided. Here's how you can do that:

Step 1: Convert the volume from milliliters (mL) to liters (L).
800 mL = 800/1000 = 0.8 L

Step 2: Use the formula for molarity (M) to calculate the moles of KNO3 required.
Molarity (M) = moles of solute / liters of solution
Rearranging the formula, moles of solute = Molarity (M) x liters of solution:
moles of KNO3 = 1.40 M x 0.8 L = 1.12 moles

Step 3: Calculate the molar mass of KNO3.
KNO3 consists of one potassium (K) atom, one nitrogen (N) atom, and three oxygen (O) atoms.
The atomic masses are as follows:
Potassium (K) = 39.10 g/mol
Nitrogen (N) = 14.01 g/mol
Oxygen (O) = 16.00 g/mol

Multiplying the atomic masses by the number of atoms in the formula and adding them together gives us the molar mass of KNO3:
Molar mass of KNO3 = 39.10 g/mol + 14.01 g/mol + (16.00 g/mol x 3) = 101.10 g/mol

Step 4: Convert moles of KNO3 to grams using the molar mass.
grams of KNO3 = moles of KNO3 x molar mass of KNO3
grams of KNO3 = 1.12 moles x 101.10 g/mol = 112.97 grams

Therefore, approximately 112.97 grams of KNO3 will be required to prepare 800 mL of 1.40 M KNO3.

To calculate the grams of KNO3 required to prepare a solution of a given concentration, you need to use the formula:

grams of solute = concentration (M) x volume (L) x molar mass (g/mol)

In this case, we have the following information:
- Concentration (M) = 1.40 M
- Volume (L) = 0.800 L (since 800 mL is equivalent to 0.800 L)
- Molar Mass of KNO3 = 101.1032 g/mol

Now, let's substitute these values into the formula:

grams of KNO3 = 1.40 M x 0.800 L x 101.1032 g/mol

Plugging in these values and performing the calculation:

grams of KNO3 = 112.224 g

Therefore, to prepare 800 mL of a 1.40 M KNO3 solution, you will need 112.224 grams of KNO3.

How many moles KNO3 will you need? That is M x L = moles KNO3.

Then moles KNO3 = grams KNO3/molar mass KNO3.