<span>Which of the following is an electronic device that measures pH?
</span><span>a. a pH meter</span>
Answer:
8.937g/cm³
Explanation:
To answer this question we need to know that, in 1 unit FCC cell you have:
Edge length = √8 * R
<em>Volume = 8√8 * R³</em>
<em>And there are 4 atoms per unit cell</em>
<em />
<em>Mass of 4 atoms in g:</em>
4 atom * (1mol / 6.022x10²³atom) * (63.55g / mol) = 4.221x10⁻²²g
<em />
<em>Volume in cm³:</em>
0.1278nm * (1x10⁻⁷cm / 1nm) = 1.278x10⁻⁸cm
Volume = 8√8 * (1.278x10⁻⁸cm)³
Volume = 4.723x10⁻²³cm³
And density is:
4.221x10⁻²²g / 4.723x10⁻²³cm³ =
<h3>8.937g/cm³</h3>
Answer:
2H2O2(aq)→ 2H2O(l) O2(g) : The oxidation number of oxygen for each compound is -1, -2, 0
Explanation:
In peroxides the oxidation state of oxygen is -1, since one oxygen bonds to the other oxygen and a hydrogen and the bound oxygen captures the electron of the remaining hydrogen. Through a scheme would be
H --- O --- O --- H
We remember that oxygen needs two electrons to get to have the configuration of the nearest noble gas (Lewis octet rule). In Peroxides, the oxygen is linked by covalent bonds. If we take it strictly, peroxide is a grouping of two oxygen, having the whole valence -2. which is why it is usually said that it is when oxygen has a valence -1
As we said the oxidation state is -2, the one that appears in the water molecule, since Hydrogen acts with valence +1 and it is 2 atoms that give up electrons to compensate for oxygen.
In the O2 it acts with valence 0 since we talk about gas in its elementary state. All diatomic molecules in their elemental state, generally gases or metals in solid state, act with a valence of 0.
Answer:
2.8 m
Explanation:
From the question given above, the following data were obtained:
Number of mole KBr = 0.210 mole
Mass of water = 0.075 kg
Molality of KBr =?
Molality is simply defined as the mole of solute per unit kg of water. Mathematically, it can be expressed as follow:
Molality = mole of solute / Kg of water.
With the above formula, we can obtain the molality of the KBr solution. This can be obtained as follow:
Number of mole KBr = 0.210 mole
Mass of water = 0.075 kg
Molality of KBr =?
Molality = mole of solute / Kg of water.
Molality = 0.210 / 0.075
Molality = 2.8 m
Therefore, the molality of the KBr solution is 2.8 m.
