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chubhunter [2.5K]

3 years ago

12

An advertising sign gives off red and green light. a. Which light has higher energy? b. One of the colors has a wavelength of 68

0 nm and the other has a wavelength of 500. Which color has which wavelength?

1 answer:

alekssr [168]3 years ago

4 0

A would be right sorry if wrong

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The layering of eroded sediments is called:

Aleks [24]

4. the rock cycle is the layering of eroded sediments

6 0

3 years ago

If you have access to stock solutions of 1.00 M H3PO4, 1.00 M of HCl, and 1.00 M NaOH solution, (and distilled water of course),

garri49 [273]

Answer:

0.10L of 1.00M of H₃PO₄ and 0.1613L of 1.00M NaOH

Explanation:

The pKa's of phosphoric acid are:

H₃PO₄/H₂PO₄⁻ = 2.1

H₂PO₄⁻/HPO₄²⁻ = 7.2

HPO₄²⁻/PO₄³⁻ = 12.0

To make a buffer with pH 9.40 we need to convert all H₃PO₄ to H₂PO₄⁻ and an amount of H₂PO₄⁻ to HPO₄²⁻

To have a 50mM solution of phosphoures we need:

2L * (0.050mol / L) = 0.10 moles of H₃PO₄

0.10 mol * (1L / mol) = 0.10L of 1.00M of H3PO4

To convert the H₃PO₄ to H₂PO₄⁻ and to HPO₄²⁻ must be added NaOH, thus:

H₃PO₄ + NaOH → H₂PO₄⁻ + H₂O + Na⁺

H₂PO₄⁻ + NaOH → HPO₄²⁻ + H₂O + Na⁺

Using H-H equation we can find the amount of NaOH added:

pH = pKa + log [A⁻] / [HA] <em>(1)</em>

<em>Where [A-] is conjugate base, HPO₄²⁻ and [HA] is weak acid, H₂PO₄⁻</em>

<em>pH = 7.40</em>

<em>pKa = 7.20</em>

[A-] + [HA] = 0.10moles <em>(2)</em>

Replacing (2) in (1):

7.40 = 7.20 + log 0.10mol - [HA] / [HA]

0.2 = log 0.10mol - [HA] / [HA]

1.5849 = 0.10mol - [HA] / [HA]

1.5849 [HA] = 0.10mol - [HA]

2.5849[HA] = 0.10mol

[HA] = 0.0387 moles = H₂PO₄⁻ moles

That means moles of HPO₄²⁻ are 0.10mol - 0.0387moles = 0.0613 moles

The moles of NaOH needed to convert all H₃PO₄ in H₂PO₄⁻ are 0.10 moles

And moles needed to obtain 0.0613 moles of HPO₄²⁻ are 0.0613 moles

Total moles of NaOH are 0.1613moles * (1L / 1mol) = 0.1613L of 1.00M NaOH

Then, you need to dilute both solutions to 2.00L with distilled water.

4 0

3 years ago

Electron configurations are a shorthand form of an orbital diagram, describing which orbitals are occupied for a given element.

kipiarov [429]

Answer:

[Ar] 3d10 4s2 4p3 is shorthand, 1s22s22p63s23p63d104s24p3 long hang

Explanation:

The shorthand is made using the lowest & closest noble gas, and picking up where it leaves off as follows, and longhand is made from a followed pattern you can easily find

3 0

3 years ago

Read 2 more answers

The temperature of a sample of water changes from 10°C to 20°C when the water absorbs 100 calories of heat. What is the mass of

Vlad1618 [11]

Answer:

10 g

Explanation:

Right from the start, just by inspecting the values given, you can say that the answer will be

10 g

.

Now, here's what that is the case.

As you know, a substance's specific heat tells you how much heat is needed to increase the temperature of

1 g

of that substance by

1

∘

C

.

Water has a specific heat of approximately

4.18

J

g

∘

C

. This tells you that in order to increase the temperature of

1 g

of water by

1

∘

C

, you need to provide

4.18 J

of heat.

Now, how much heat would be required to increase the temperature of

1 g

of water by

10

∘

C

?

Well, you'd need

4.18 J

to increase it by

1

∘

C

, another

4.18 J

to increase it by another

1

∘

C

, and so on. This means that you'd need

4.18 J

×

10

=

41.8 J

to increase the temperature of

1 g

of water by

10

∘

C

.

Now look at the value given to you. If you need

41.8 J

to increase the temperature of

1 g

of water by

10

∘

C

, what mass of water would require

10

times as much heat to increase its temperature by

10

∘

C

?

1 g

×

10

=

10 g

And that's your answer.

Mathematically, you can calculate this by using the equation

q

=

m

⋅

c

⋅

Δ

T

, where

q

- heat absorbed/lost

m

- the mass of the sample

c

- the specific heat of the substance

Δ

T

- the change in temperature, defined as final temperature minus initial temperature

Plug in your values to get

418

J

=

m

⋅

4.18

J

g

∘

C

⋅

(

20

−

10

)

∘

C

m

=

418

4.18

⋅

10

=

10 g

5 0

3 years ago

How does the body react when the outside temperature gets too hot

mr_godi [17]

When temperatures rise, the body reacts by increasing blood flow to the skin's surface, taking the heat from within the body to the surface. This means sweat. ... If, as in the UK, our skin temperature is warmer than the external temperature we are also able to lose heat to the environment, termed 'dry heat loss'.

6 0

2 years ago