Answer:
you must add 50 mL
Explanation:
Hi
KOH is a strong base and by adding 100mL 0.05M you will have an amount of 5 millimol.
NaCN is a base and by adding 50 mL 0,150 M you will have an amount of 7,5 mmol.
HCl is a acid and by adding 200 mL 0,075 M you will have an amount of 15 mmol.
The acid reacts with the bases leaving 2.5 mmol unreacted.
Na3PO4 is a base and by adding 50 mL 0,1 M you will have an amount of 5 mmol.
The 2.5 mmol of acid react with the base PO4 ^ -3 forming a regulatory solution of PO4 ^ -3 and HPO4 ^ -2 of pKa 2.12
5 mmol of acid (HNO3) must be added to obtain a regulatory solution formed by the same amount of HPO4 ^ -2 (2.5 mmol) and H2PO4 ^ -1 (2.5 mmol) with pKa 7.21
Considering a quantity of 5 mmol of HNO3 of concentration 0.1 M, 50 mL must be added.
To calculate the pH of the regulatory solution you should consider pH = pKa × Ca / Cb pH = 7.21 × 2.5 / 2.5 = 7.21 Being in the same solution the volume is the same and can be simplified to achieve a faster calculation.
successes with your homework
Answer:
0.2934 g of N₂
Explanation:
The balance chemical equation for given reaction is as follow;
2 NH₃ + 3 CuO → 3 Cu + N₂ + 3 H₂O
Step 1: <u>Calculate Moles of CuO as;</u>
Moles = Mass / M.Mass
Moles = 2.5 g / 79.54 g/mol
Moles = 0.0314 moles of CuO
Step 2: <u>Find out moles of N₂ as;</u>
According to equation,
3 moles of CuO produced = 1 mole of N₂
So,
0.0314 moles of CuO will produce = X moles of N₂
Solving for X,
X = 0.0314 mol × 1 mol / 3 mol
X = 0.0104 moles of N₂
Step 3: <u>Calculate Mass of N₂ as;</u>
Mass = Moles × M.Mass
Mass = 0.0104 mol × 28.01 g/mol
Mass = 0.2934 g of N₂
Urea is diffused more slowly because it’s larger than sodium.
