Answer:
The correct answer is: d. The pKa of the chosen buffer should be close to the optimal pH for the biochemical reaction.
Explanation:
The buffer resist or maintain the change in pH in case of Acid or basic addition to the solution. The buffer capacity should be within one or two pH units when compared to the optimal pH.
Thus it is important to select a buffer with pKa close to the optimum pH of the reaction because the ability for the buffer to maintain the pH is is great at the pH close to pKa.
Answer: Carbon dioxide is a pure substance.
Explanation: A pure substance is defined when a substance has a single type of molecule. If more than 1 type of molecule is present in a substance, then it is considered as a mixture.
- Soda is basically a mixture of water and carbon dioxide. More than 1 type of molecule is present.
- Gasoline is a mixture of may gases. More than 1 type of molecule is present.
- Salt water contains salt and water molecules, hence it is considered as a mixture.
- Carbon dioxide has only 1 type of molecule which is
molecules. Hence, it is a pure substance.
Answer:
Most atoms do not have eight electrons in their valence electron shell. Some atoms have only a few electrons in their outer shell, while some atoms lack only one or two electrons to have an octet. In cases where an atom has three or fewer valence electrons, the atom may lose those valence electrons quite easily until what remains is a lower shell that contains an octet. Atoms that lose electrons acquire a positive charge as a result because they are left with fewer negatively charged electrons to balance the positive charges of the protons in the nucleus. Positively charged ions are called cations. Most metals become cations when they make ionic
The number of grams of Cl2 formed when 0.385 mol HCl reacts with an excess of O2 is 13.6675 g.
<h3>What are moles?</h3>
A mole is defined as 6.02214076 × 
of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
Given data:
Moles of hydrochloric acid = 0.385 mol
Mass of chlorine gas =?
Chemical equation:
4HCl + O₂ → 2Cl₂ + 2H₂O
Now we will compare the moles of Cl₂ with HCl.
HCl : Cl₂
4 : 2
0.385 : 2÷4× 0.385 = 0.1925 mol
Oxygen is present in excess that's why the mass of chlorine produced depends upon the available amount of HCl.
Mass of Cl₂ :
Mass of Cl₂ = moles × molar mass
Mass of Cl₂ =0.1925 mol × 71 g/mol
Mass of Cl₂ = 13.6675 g
Hence, the number of grams of Cl2 formed when 0.385 mol HCl reacts with an excess of O2 is 13.6675 g.
Learn more about moles here:
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Explanation:
When OH- (as in potassium hydroxide) is added, it reacts with the acid (HOCl) to reduce the amount of HOCl and increase the concentration of sodium hypochlorite.
Potassium hydroxide will react with the hypochlorous acid to produce hypochlorite ions. In the process, some of the weak acid will be consumed, along with the added strong base.
This occurs as follows:
HClO(aq) + KOH(aq) → KClO(aq) + H2O(l)
since water is formed, this maintains the pH. Thus ...
A. The number of moles of HClO will decrease. - TRUE
B. The number of moles of ClO- will increase. - TRUE
C. The equilibrium concentration of H3O+ will remain the same. - TRUE
D. The pH will decrease. - FALSE
E. The ratio of [HClO] / [ClO-] will decrease. -TRUE. It will decrease as HClO goes down and ClO- goes up.
