Question

Tris base has a molecular weight of 121 g/mol. How many grams of tris base would you need to make 250ml of a 200mM SOLUTION

Answer 1

We need 6.05 grams of tris base to make this solution

Step-by-step explanation:

Step 1: Data given

Molecular weight of tris base = 121 g/mol

volume of solution = 250 mL = 0.250 L

Molarity = 200 mM = 0.200 M

Step 2: Calculate moles tris base

Moles tris base = molarity * volume

Moles tris base = 0.200 M * 0.250 L

Moles tris base = 0.05 moles

Step 3: Calculate mass of tris base

Mass tris base = moles tris base * molar mass

Mass tris base = 0.05 moles * 121 g/mol

Mass tris base = 6.05 grams

We need 6.05 grams of tris base to make this solution

Answer 2

6.05 g

Step-by-step explanation:

Molarity of a substance , is the number of moles present in a liter of solution .

M = n / V

M = molarity

V = volume of solution in liter ,

n = moles of solute ,

From the question ,

M = 200mM

Since,

1 mM = 10⁻³ M

M = 200 * 10⁻³ M

V = 250 mL

Since,

1 mL = 10⁻³ L

V = 250 * 10⁻³ L

The moles can be calculated , by using the above relation,

M = n / V

Putting the respective values ,

200 * 10⁻³ M = n / 250 * 10⁻³ L

n = 0.05 mol

Moles is denoted by given mass divided by the molecular mass ,

Hence ,

n = w / m

n = moles ,

w = given mass ,

m = molecular mass .

From the question ,

m = 121 g/mol

n = 0.05 mol ( calculated above )

The mass of tri base can be calculated by using the above equation ,

n = w / m

Putting the respective values ,

0.05 mol = w / 121 g/mol

w = 0.05 mol * 121 g/mol

w = 6.05 g