Options are provided in the given question, so the complete question is as follows:
Laboratory equipment is cleaned and properly stored after use primarily so that —
A. chemical products can be measured and recorded as data
B. time is saved in setting up the next experiment
C. toxic materials can be kept in the laboratory
D. the possibility of contamination in the laboratory is minimized
Answer:
D. the possibility of contamination in the laboratory is minimized
Explanation:
After the completion of experiments, all the laboratory equipment should be cleaned and properly stored to minimize the possibility of contamination in the laboratory.
Any contamination in the laboratory can affect the experiment and will not give an accurate result, so it is important to clean and store the equipment properly.
Hence, the correct answer is "D".
Poor etiquette is the answer
Molarity is defined as the number of moles of solute in 1 L of solution
mass fo KCl in the solution is - 5.0 g
number of moles of KCl - 5.0 g/ 74.5 g/mol = 0.067 mol
number of moles of KCl in 100 mL - 0.067 mol
therefore number of KCl moles in 1 L - 0.067 / 100 mL x 1000 mL = 0.67 M
molarity of KCl is 0.67 M
Answer:
pH=3.38
Explanation:
We are given the concentrations of the weak acid and its conjugate base so we need to use the henderson hasslebalch equation
pH=pKa + log (concentration A-/concentration of HA)
A- : conjugate base NaC3H5O3
HA: weak acid HC3H5O3
so if we plug in what we are given
pH= 3.08 + log (1M/.5M)
pH= 3.38
NO2- +7H+ + 6e->> NH3 + 2H2O ( N goes from +3 to -3)
<span>Al + 2 H2O >> AlO2- + 4H+ + 3e- </span>
<span>NO2- + 2Al + 2H2O >> NH3 + 2AlO2- + H+ </span>
<span>add OH- on the left and on the right </span>
<span>NO2- + 2 Al + H2O + OH- >> NH3 + 2 AlO2-</span>
