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vagabundo [1.1K]
3 years ago
7

How much of a sample remains after five half-lives have occurred?

Chemistry
1 answer:
hammer [34]3 years ago
5 0
The answer is 1/32

The first half-life, we have 1 • 1/2 = 1/2 left.
After two: 1/2 • 1/2 = 1/4
Three: 1/4 • 1/2 = 1/8
Four: 1/8 • 1/2 = 1/16
And five: 1/16 • 1/2 = 1/32.
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What is the pH of a solution that is 0.40 M NaBrO and 0.50 M HBrO (hypobromous acid) (Ka for HBrO = 2.3 x 10^-9)
Pie

Answer

pH=8.5414

Procedure

The Henderson–Hasselbalch equation relates the pH of a chemical solution of a weak acid to the numerical value of the acid dissociation constant, Kₐ. In this equation, [HA] and [A⁻] refer to the equilibrium concentrations of the conjugate acid-base pair used to create the buffer solution.

pH = pKa + log₁₀ ([A⁻] / [HA])

Where

pH = acidity of a buffer solution

pKa = negative logarithm of Ka

Ka =acid disassociation constant

[HA]= concentration of an acid

[A⁻]= concentration of conjugate base

First, calculate the pKa

pKa=-log₁₀(Ka)= 8.6383

Then use the equation to get the pH (in this case the acid is HBrO)

pH=8.6383+\log_{10}(\frac{0.40\text{ M}}{0.50\text{ M}})=8.5414

8 0
1 year ago
Collision of which two types of plates create the deepest earthquakes? Why do you think this is?
Elis [28]

Answer:

The collision of oceanic plates and any other plates in which the oceanic plate slides beneath the other plate creates the biggest earth quakes. Most of these earth quakes occur beneath the sea or oceans and can cause volcanic eruptions as well. Tsunami is another oceanic event that occurs due to earth quakes occurring due to shifting of plates beneath the sea.

7 0
3 years ago
Briefly discuss interpretations of your observations and results. Discuss how your observations illustrated LeChatelier's princi
Dvinal [7]

Answer:

Le Chatelier's principle can be applied in explaining the results

Explanation:

According to Le Chatelier's principle, when a constraint such as a change in concentration in this case is imposed on a chemical system in equilibrium, the system will adjust itself in such a way as to annul the constraint imposed.

Hence, when the color of the solution was more like that of the control, the reaction would shift towards the left. Similarly, when the color was more like it was towards the reactant, the reaction would shift towards the right.

If we were to prepare calcium oxalate, we should prepare it in a base solution. This is because when the base was added to calcium oxalate, it did not form any precipitate but when an acid was added to the calcium oxalate, it formed a precipitate.

4 0
3 years ago
What patterns in the rock layer fossils helped you identify an extinction?
Dafna11 [192]
Often, the rock layers bookending the mass extinction are noticeably different in their compositions. These changes in the rocks show the effects of environmental disturbances that triggered the mass extinction and sometimes hint at the catastrophic cause of the extinction
8 0
3 years ago
Read 2 more answers
A scientist wants to make a solution of tribasic solution phosphate, na3po4, for a laboratory experiment. How many grams of na3p
timurjin [86]

Answer:

55.75g

Explanation:

From

m/M = CV

Where

m= required mass of solute

M= molar mass of solute

C= concentration of solution

V= volume of solution=675ml

Molar mass of solute= 3(23) + 31 + 4(16)= 69+31+64=164gmol-1

Number of moles of sodium ions present= 1.5× 675/1000= 1.01 moles

Since 1 mole of Na3PO4 contains 3 moles of Na+

It implies that 1.01/3 moles of Na3PO4 are present in solution= 0.34moles

mass of Na3PO4= number of moles × molar mass= 0.34 × 164 =55.75g

3 0
4 years ago
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