Answer:
0.241 × 10³⁰ molecules
Explanation:
Given data:
Mass of Cr(HCO₃)₃ = 9.273 × 10⁷ g
Number of molecules = ?
Solution:
Number of moles = 9.273 × 10⁷ g/ 235 g/mol
Number of moles = 0.04× 10⁷ mol
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
18 g of water = 1 mole = 6.022 × 10²³ molecules of water
1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen
For 0.04× 10⁷ moles of Cr(HCO₃)₃:
0.04× 10⁷ moles × 6.022 × 10²³ molecules / 1 mol
0.241 × 10³⁰ molecules
A: mouth. Chemical digestion begins in the mouth when enzymes in saliva begin to break down carbohydrates. Most chemical changes in digestion occur in the small intestine. Large molecules of food are broken down into smaller molecules that can be absorbed by our cells.
Answer:
pH of resulting solution = 7.98
Explanation:
The balanced equation
HA + NaOH - Na+ + A- + H2O
Number of moles of A = Number of moles of HA = Number of moles of NaOH
= 35.8/1000 * 0.020 = 0.000716 mol
Initial concentration of A = 0.000716/0.0608 = 0.01178 M
pKb = 14 – pKa = 14 -3.9 = 10.1
Kb = 10^{-Kb} = 10^{-10.1} = 7.943 * 10^-11
Kb = [HA][OH-]/[A-]
Kb = a^2/(0.01178 -a) = 7.943 * 10^-11
a^2 + 7.943 * 10^-11 a – 9.357 * 10^-13 = 0
a = 9.673 * 10^-7
OH- = a = 9.673 * 10^-7 M
pOH = -log [OH-] = -log (9.673 * 10^-7) = 6.02
pH = 14-6.02 = 7.98
