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3 years ago

Students were asked to place a mint in their mouths and determine how long it took for the mint to dissolve. The

Chemistry

1 answer:

saveliy_v [14]3 years ago

4 0

B. The time is likely between 40 - 80 seconds.

<u>Explanation:</u>

One group of students were asked to leave a whole mint in their mouth, not moving it around, and let it dissolve, which takes very long time to dissolve since there is lower frequency of collision among the saliva particles and mint.

Another group swirled a whole mint around in their mouths, so the frequency of collision between the saliva and the mint particles increases, there by increase in dissolving capacity, but the timing will be lesser when compared to other groups used mints broken into smaller pieces.

So the time for swirling is likely between 40 - 80 seconds.

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What are two objects from home that have energy and how do I know they have energy?

IRINA_888 [86]

Light bulb -it produces heat and light
toaster - it produces heat and the metal strips glow producing light

7 0

3 years ago

it takes 463 kJ/mol to break an oxygen-hydrogen single bond. calculate the maximum wavelength of light for which an oxygen-hydro

Marianna [84]

Answer:

<u>2.59 × 10⁻⁷ m = 259 nm</u>

Explanation:

You need to calculate the wavelength of a photon with an energy equal to 463 kJ/mol, which is the energy to break an oxygen-hydrogen atom.

The energy of a photon and its wavelength are related by the Planck - Einstein equation:

E = hν,

Where:

E = energy of a photon,

h = Planck constant (6.626 × 10⁻³⁴ J . s) and

ν = frequency of the photon.

And:

ν = c / λ

Where:

c = speed of light (3.00 × 10⁸ m/s in vacuum)

λ = wavelength of the photon

Thus, you can derive:

E = h c / λ

Solve for λ:

λ = h c / E

Before substituting the values, convert the energy, 463 kJ/ mol, to J/bond

463 kJ/ mol × 1,000 J/kJ × 1 mol / 6.022 × 10 ²³ atom × 1 bond / atom

= 7.69×10²³ J / bond

Substitute the values and use the energy of one bond:

λ = 6.626 × 10⁻³⁴ J . s × 3.00 × 10⁸ m/s / 7.69×10²³ J = 2.59 × 10⁻⁷ m

The wavelength of light is usually shown in nanometers:

2.59 × 10⁻⁷ m × 10⁹ nm / m = 259 nm ← answer

6 0

3 years ago

If the rate of a reaction increases by a factor of 64 when the concentration of reactant increases by a factor of 4, what is the

igomit [66]

The reaction is of order three with respect to the reactant.

<h3>Explanation</h3>

The rate of a reaction of order n about a certain reactant is proportion to the concentration of that reactant raised to the n-th power. This is true only if concentrations of any other reactants stay constant in the whole process.

In other words, Rate = constant × [Reactant]ⁿ, Rate ∝ [Reactant]ⁿ. (The symbol "∝" reads "proportional to".)

In this question,

[4 × Reactant]ⁿ ÷ [Reactant]ⁿ = 64.

In other words, 4ⁿ = 64, where n is the order of the reaction with respect to this reactant.

It might take some guesswork to find the value of n. Alternatively, n can be solved directly with a calculator using logarithms. Taking natural log of both sides:

$\ln{4^n} = \ln{64}\\n\; \ln{4} = \ln{64}\\n = \frac{\ln{64}}{\ln{4}} = 3$ .