A 4 gram metal object displaces 2 mL of water in a graduated cylinder. What is the density of the metal object?

If a buffer solution is 0.220 M in a weak acid ( Ka=7.4×10−5) and 0.540 M in its conjugate base, what is the pH?

valkas [14]

Answer: the pH of the solution is 4.52

Explanation:

Consider the weak acid as Ha, it is dissociated as expressed below

HA H⁺ + A⁻

the Henderson -Haselbach equation can be expressed as;

pH = pKa + log( [A⁻] / [HA])

the weak acid is dissociated into H⁺ and A⁻ ions in the solution.

now the conjugate base of the weak acid HA is

HA(aq) {weak acid} H⁺(aq) + A⁻(aq) {conjugate base}

so now we calculate the value of Kₐ as well as pH value by substituting the values of the concentrations into the equation;

pKₐ = -logKₐ

pKₐ = -log ( 7.4×10⁻⁵ )

pKₐ = 4.13

now thw pH is

pH = pKₐ + log( [A⁻] / [HA])

pH = 4.13 + log( [0.540] / [0.220])

pH = 4.13 + 0.3899

pH = 4.5199 = 4.52

Therefore the pH of the solution is 4.52

6 0

3 years ago

16. Explain why antifreeze is used in vehicle radiators. Use your knowledge of the properties of

Fynjy0 [20]

Answer:

Antifreeze is whats used to keep your engine cool without freezing.

Explanation:

it keeps the engine from overheating.

It also prevents corrosion.

Here is a quote from google "Antifreeze works because the freezing and boiling points of liquids are “colligative” properties. This means they depend on the concentrations of “solutes,” or dissolved substances, in the solution. A pure solution freezes because the lower temperatures cause the molecules to slow down"

That quote is from "The Science Behind Antifreeze"

If you have any questions feel free to ask in the comments.

4 0

3 years ago

Part A

Roman55 [17]

These are two questions and two answers

Question 1.

Answer:

7.33 × 10 ⁻³ c

Explanation:

1) Data:

a) m = 9.11 × 10⁻³¹ kg

b) λ = 3.31 × 10⁻¹⁰ m

c) c = 3.00 10⁸ m/s

d) s = ?

2) Formula:

The wavelength (λ), the speed (s), and the mass (m) of the particles are reltated by the Einstein-Planck's equation:

λ = h / (m.s)

h is Planck's constant: h= 6.626×10⁻³⁴J.s

3) Solution:

Solve for s:

s = h / (m.λ)

Substitute:

s = 6.626×10⁻³⁴J.s / ( 9.11 × 10⁻³¹ kg × 3.31 × 10⁻¹⁰ m) = 2.20 × 10 ⁶ m/s

To express the speed relative to the speed of light, divide by c = 3.00 10⁸ m/s

s = 2.20 × 10 ⁶ m/s / 3.00 10⁸ m/s = 7.33 × 10 ⁻³

Answer: s = 7.33 × 10 ⁻³ c

Question 2.

Answer:

2.06 × 10 ⁻³⁴ m.

Explanation:

1) Data:

a) m = 45.9 g (0.0459 kg)

b) s = 70.0 m/s

b) λ = ?

2) Formula:

Macroscopic matter follows the same Einstein-Planck's equation, but the wavelength is so small that cannot be detected:

λ = h / (m.s)

h is Planck's constant: h= 6.626×10⁻³⁴J.s

3) Solution:

λ = h / (m.s)

Substitute:

λ = 6.626×10⁻³⁴J.s / ( 0.0459 kg × 70.0 m/s) = 2.06 × 10 ⁻³⁴ m

As you see, that is tiny number and explains why the wave nature of the golf ball is undetectable.

Answer: 2.06 × 10 ⁻³⁴ m.

5 0

3 years ago

What happens when lead nitrate and potassium iodide are mixed?

lisov135 [29]

Answer:

Explanation: A yellow precipitate o lead iodide is formed. see equation of reaction below: $2KI + Pb(NO3)2$ → $PbI2 + 2K(NO3)2$

Th PbI2 is the insoluble yellow precipitate

7 0

3 years ago

If the length of a string increases 2 times but the mass of the string remains constant, the new density of the string will equa

Genrish500 [490]

If the length of a string increases 2 times but the mass of the string remains constant, the original density will be multiplied by a factor mathematically given as

v=1.414 times

<h3>Will the new density of the string equal the original density multiplied by what factor?</h3>

Generally, the equation for the volume is mathematically given as

v = sqt(TL/m)

Where

density = mass/length

Therefore

$v2/v1 = \sqrt{L2/L1}$

$v2/v1 = \sqrt{2}$

In conclusion,v ratio will give us

v=1.414 times