It is not just lab chemicals but also common household substances that can be classified as acidic, basic, and neutral materials
. This categorization is based on the concentration of hydrogen ion (H+), or hydronium ion (H3O+), and hydroxide ion (OH-) present in the solutions. Based on these ion concentrations, the pH or pOH can be calculated giving a quantitative assessment. Additionally, litmus paper or pH paper can be used to qualitatively determine if the solution is acidic, basic, or neutral. Red litmus paper turns blue in acid. Blue litmus paper turns red in base. pH paper gives a more precise pH number based on the color the pH paper turns when a small amount of solution is placed on the paper.
Most materials are either acidic or basic. Baking soda, bleach, codeine, detergent, egg whites, household cleaners, and seawater are basic because they have a high concentration of hydroxide ions in solution and pH above 7. Acid rain, beer, coffee, lemon juice, maple syrup, mouth wash, pickles, rain, soda, tea, tomatoes, and vinegar are acidic because they have a high concentration of hydrogen ions in solution and pH below 7. A few solutions have neutral pH due an equal concentration of hydrogen ions and hydroxide ions. Water is the only truly neutral substance but human blood, milk, plant food, saliva, and tofu are very close to neutral pH with nearly equal hydrogen ion and hydroxide ion concentration and pH near 7.
Listed in the Item Bank are key terms and expressions, each of which is associated with one of the columns. Some terms may display additional information when you click on them. Drag and drop each item into the correct column. Order does not matter.
Most materials are either acidic or basic. Baking soda, bleach, codeine, detergent, egg whites, household cleaners, and seawater are basic because they have a high concentration of hydroxide ions in solution and pH above 7. Acid rain, beer, coffee, lemon juice, maple syrup, mouth wash, pickles, rain, soda, tea, tomatoes, and vinegar are acidic because they have a high concentration of hydrogen ions in solution and pH below 7. A few solutions have neutral pH due an equal concentration of hydrogen ions and hydroxide ions. Water is the only truly neutral substance but human blood, milk, plant food, saliva, and tofu are very close to neutral pH with nearly equal hydrogen ion and hydroxide ion concentration and pH near 7.
Listed in the Item Bank are key terms and expressions, each of which is associated with one of the columns. Some terms may display additional information when you click on them. Drag and drop each item into the correct column. Order does not matter.
1 answer:
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Answer:
tex]\lambda_{Be}[/tex] = 22.78 nm
Explanation:
Bohr's model for the hydrogen atom has been used by other atoms with a single electric charge by changing the number of charges by the charge of the new atom (atomic number)
= k e² / 2a₀ (1 /n²)
ao = h'² / k m e² h' = h/2πi
For another atom with a single electron in the last layer
a₀ ’= h’² / k m (Ze)²
a₀ ’= a₀ / Z²
Therefore, when replacing in the equation
= - Z² Eo/n²
E₀ = 13,606 eV
The transition occurs when the electron stops from one level to another
-
= Z² E₀ (1 / n² - 1 / m²) = Z² ΔE
Let's relate this expression to the wavelength
c = λ f
E = h f
E = h c /λ
h c / λ = Z² ΔE
λ = 1 / Z² (hc / ΔE)
λ = 1 / Z² λ_hydrogen
Let's apply this last equation to our case
Lithium Z = 3
= - 9 Eo / n²
40.5 10-9 = 1/9 λ_hydrogen
Beryllium Z = 4
λ = 1/16 λ_hydrogen
Let's write our two equations is and solve
40.5 10-9 = 1/9 λ_hydrogen
tex]\lambda_{Be}[/tex] = 1/ 16 λ_hydrogen
40.5 10⁻⁹ = 1/9 (16 )
tex]\lambda_{Be}[/tex] = 40.5 9/16
tex]\lambda_{Be}[/tex] = 22.78 nm