Answer:
[HF]₀ = 0.125M
Explanation:
NaOH + HF => NaF + H₂O
Adding 20ml of 0.200M NaOH into 25ml of HF solution neutralizes 0.004 mole of HF leaving 0.004 mole NaF in 0.045L with 0.001M H⁺ at pH = 3. This is 0.089M NaF and 0.001M HF remaining.
=> 45ml of solution with pH = 3 and contains 0.089M NaF from titration becomes a common ion problem.
HF ⇄ H⁺ + F⁻
C(eq) [HF] 10⁻³M 0.089M (<= soln after adding 20ml 0.200M NaOH)
Ka = [H⁺][F⁻]/[HF]₀ => [HF]₀ = [H⁺][F⁻]/Ka
[HF]₀ = (0.001)(0.089)/(7.1 x 10⁻⁴) M = 0.125M
Answer:
6.00%
Explanation:
Step 1: Given data
Accepted value for the number of calories in a Bananas Foster: 300 calories
Measured value for the number of calories in a Bananas Foster: 318 calories
Step 2: Calculate the percent error in the measure
We will use the following expression.
%error = |accepted value - experimental value|/ accepted value × 100%
%error = |300 cal - 318 cal|/ 300 cal × 100% = 6.00%
Answer:
Chemists investigate the properties of matter at the level of atoms and molecules. They measure proportions and reaction rates in order to understand unfamiliar substances and how they behave, or to create new compounds for use in a variety of practical applications.
Explanation:
Which is a correct description of the organization of subatomic particles in atoms?
Protons and neutrons are tightly packed into a small nucleus. Electrons occupy the space
outside the nucleus
hope this helps.
Answer:
See image attached and explanation
Explanation:
The stratospheric ozone layer is very important in absorbing high-energy ultraviolet radiation that is harmful to living systems on earth. The concentration of ozone in the stratosphere is determined by both thermal and photochemical pathways for its decomposition. Nitric oxide, NO, is a trace constituent in the stratosphere that reacts with ozone to form nitrogen dioxide, NO2, and the diatomic oxygen molecule. The nitrogen-oxygen bond in NO2 is relatively weak. When an NO2 molecule encounters an oxygen atom, it transfers an oxygen, forming O2 and NO. The chemical reactions involved are formations of NO2 following by reaction of NO2 with atomic oxygen for form NO and O2. The sum of both reactions show that the overall reaction is simply the reaction of ozone with atomic oxygen to form two molecules of molecular oxygen. Hence, NO only serves as a catalyst, it does not undergo a permanent change itself.
