PH + pOH = 14 ⇒ pOH = 14 - pH
pOH = 14 - 2.5
pOH = 11.5
[H⁺] = 10^(-pH) = 10^(-2.5)
[H⁺] = 0.003 M
[OH⁻] = 10^(-pOH) = 10^(-11.5) = 3 × 10⁻¹² M
[OH⁻] = 3 × 10⁻¹² M
pH = 2.5 implies one significant digit
Answer:
A. a system that can be affected by the outside environment, by an exchange of matter or energy
The number of grams of NaOH that are needed to make 500 ml of 2.5 M NaOH solution
calculate the number of moles =molarity x volume/1000
= 2.5 x 500/1000 = 1.25 moles
mass = moles x molar mass of NaOH
= 1.25 x40= 50 grams of NaOH
Answer:
26.25 mL
Explanation:
This is a dilution problem. First, let us calculate the volume of final solution needed:
The dog weighs 50 pounds and the sedative is administered at 0/7 ml per pound. Hence:
50 x 0.7 = 35 mL
A total volume of 35 mL, 2.5% solution of the sedative will be needed.
But 10% solution is available. There needs to be a dilution with saline water, but what volume of the 10% solution would be diluted?
initial volume = ?
final volume = 35 mL
initial concentration = 10%
final concentration = 2.5%
Using dilution equation:
initial concentration x initial volume = final concentration x final volume
initial volume = 
= 2.5 x 35/10 = 8.75 mL
Hence, 8.75 mL of the 10% pre-mixed sedative will be required.
But 35 mL is needed? The 8.75 mL is marked up to 35 mL with saline water.
35 - 8.75 = 26.25 mL
<em>Therefore, 26.25 mL of saline water will be added to 8.75 mL of the 10% pre-mixed sedative to give 2.5%, 35 mL needed for the dog.</em>