Answer:
Conditioning two or three times will insure that the concentration of titrant is not changed by a stray drop of water.
Explanation:
"Check the tip of the buret for an air bubble. To remove an air bubble, whack the side of the buret tip while solution is flowing".
Yeas, the reaction is balanced
Answer:
These two are equivalent and valid:
Explanation:
The molecular superscripts for each atom in the <em>molecular formula</em> are determined by the number of times that the mass of the<em> empirical formula</em> is contained in the<em> molar mass</em>.
<u />
<u>1. Determine the mass of the empirical formula:</u>
:
Atomic masses:
- O: 15.999g/mol
- C: 12.011g/mol
- N: 14.007g/mol
- Cl: 35.453g/mol
Total mass:
- 15.999g/mol + 12.011g/mol + 14.007g/mol + 35.453g/mol = 77.470g/mol
<u />
<u>2. Divide the molar mass by the mass of the empirical formula:</u>
- 232.41g/mol / 77.470g/mol = 3
<u>3. Multiply each superscript of the empirical formula by the previous quotient: 3</u>
Or:
You might also write CN as a group:
1) It was Avogadro (option E).
The full name is Amadeo Avogadro. He was a famous Italian scientific. He formulated the Law that states that same volume of gases at same temperature and pressure corresponds same number of particles.
2) Cathode rays are electrons and have the largest charge mass / ratio of fundamental particles found in the atom (option E)
For example, electrons have the same charge magnitude than protons, but the mass of the electrons is a small fraction of the mass of the protons. (1/1840)
Answer:
The correct answer is 0.61 ml
Explanation:
Nitric acid is a strong acid. That means that it dissociates completely in water as follows:
HNO₃ → H⁺ + NO₃⁻
As the dissociation is complete, the concentration of H⁺ ions is equal to the initial concentration of the acid (HNO₃). Thus, the pH can be calculated from the initial concentration of the acid:
pH= -log [H⁺] = -log [acid]
We want a nitric acid solution with a pH of 2.0. so we first calculate the concentration of acid we need:
2.0 = -log [acid]
10⁻²= [acid]
The chemist has a stock solution with C= 9.0 M and he/she wants a solution with C= 1 x 10⁻² M and V= 550 ml. We use the equation that relates the initial concentration and volume (Ci and Vi, respectively) of a solution with the final concentration and volume (Cf and Vf, respectively):
Ci x Vi = Cf x Vf
⇒ Vi= (Cf x Vf)/Ci = (1 x 10⁻² M x 550 ml)/9.0 M = 0.611 ml
Summarizing, the chemist must measure 0.611 ml of concentrated solution (9.0 M), add it to the flask and fill the flask to the mark until 550 ml in order to obtain a nitric acid solution with a pH of 2.0.
