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3 years ago

Julie finds a snail on the sidewalk and wants to know whether or not the snail moves throughout the day. She places a

Chemistry

2 answers:

jasenka [17]3 years ago

4 0

Answer:

Explanation:

AURORKA [14]3 years ago

3 0

Acting as a reference point for detecting motion

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Which of the possible compounds has a mass of 163 grams when

Simora [160]

Answer:

CH4

Explanation:

In solving this problem, we must remember that one mole of a compound contains Avogadro's number of elementary entities. These elementary entities include atoms, molecules, ions etc. Recall that one mole of a substance is the amount of substance that contains the same number of elementary entities as 12g of carbon-12. The Avogadro's number is 6.02 × 10^23.

Hence we can now say;

If 163 g of the compound contains 6.13 ×10^24 molecules

x g will contain 6.02 × 10^23 molecules

x= 163 × 6.02 × 10^23 / 6.13 × 10^24

x= 981.26 × 10^23/ 6.13 ×10^24

x= 160.1 × 10^-1 g

x= 16.01 g

x= 16 g(approximately)

16 g is the molecular mass of methane hence x must be methane (CH4)

6 0

3 years ago

A buffer solution contains a weak acid, HA , and its conjugate base, A − . The buffer solution has a pH of 5.76 , and the weak a

ludmilkaskok [199]

Answer:

The relationship is expressed as follows: $K_{a} = \frac{[H+][A-]}{[HA]}$

Explanation:

Most acidic substances are weak acids and are therefore only partially ionized in acqeous solution. We cab use the equilibrium constant for the ionization of acid to express the extent to which the weak acid ionizes. If we represent a general weak acid as HA, we can write the equation for its ionization reaction like this:

$K_{a} = \frac{[H+][A-]}{[HA]}$

To calculate the pH of a weak acid, we use the equilibrium concentration of the reacted species and product.

Take for example:

HA → H + A⁻

where A id the conjugate base.

Knowing that x amount of acid reacts, we can solve like this:

HA → H + A⁻

H+ = antilog (pH)

thus, the pH of the acid is equals to H+ (initial) - H+ (equilibrium) ≈ H+ (initial)

4 0

4 years ago

Given the half‑reactions and their respective standard reduction potentials 1. Cr 3 + + e − ⟶ Cr 2 + E ∘ 1 = − 0.407 V 2. Cr 2 +

Licemer1 [7]

Answer:

The standard reduction potential for the reduction half‑reaction of Cr(III) to Cr(s) is -0.744 V

Explanation:

Here we have

1. Cr³⁺ + e − ⟶ Cr²⁺ E⁰₁ = − 0.407 V

2. Cr²⁺ + 2 e − ⟶ Cr ( s ) E⁰₂ = − 0.913 V

To solve the question, we convert, the E⁰ values to ΔG as follows

ΔG₁ = n·F·E⁰₁ and ΔG₂ = n·F·E⁰₂

Where:

F = Faraday's constant in calories

n = Number of e⁻

ΔG₁ = Gibbs free energy for the first reaction

ΔG₂ = Gibbs free energy for the second half reaction

E⁰₁ = Reduction potential for the first half reaction

E⁰₂ = Reduction potential for the second half reaction

∴ ΔG₁ = 1 × F × − 0.407 V

ΔG₂ = 2 × F × − 0.913 V

ΔG₁ + ΔG₂ = F × -2.233 V which gives

ΔG = n × F × ΔE⁰ = F × -2.233 V

Where n = total number of electrons ⇒ 1·e⁻ + 2·e⁻ = 3·e⁻ = 3 electrons

We have, 3 × F × ΔE⁰ = F × -2.233 V

Which gives ΔE⁰ = -2.233 V /3 = -0.744 V.

7 0

3 years ago

Which is a polar molecule?

Sloan [31]

A polar molecule is when the arrangement of the atoms in molecules are unequal where one end of the molecule has a positive charge while the other end has a negative charge. Examples of a polar molecule are water, ammonia, hydrogen sulfide and sulfur dioxide. The opposite is called a nonpolar molecule.

5 0

4 years ago

What can group numbers on the periodic table help you determine?

Ilia_Sergeevich [38]

Http://www.chem4kids.com/files/elem_pertable.html this should help.

4 0

3 years ago