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kvasek [131]
3 years ago
14

A steam engine only converts 20 percent of its input energy into useful work?​

Chemistry
1 answer:
Alina [70]3 years ago
4 0

Answer:

A heat engine is a type of engine, (like the motor in a car) that produces ... Heat engines do just the opposite; they take the energy from being warm ... using a flame to heat water into steam, then using the steam to turn a turbine. ... is the percentage of energy input that the engine can convert to useful work.

Explanation:

hope this helps

and i hope its right

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A student is asked to standardize a solution of barium hydroxide. He weighs out 0.978 g potassium hydrogen phthalate (KHC8H4O4,
Sav [38]

Answer:

(A) 0.129 M

(B) 0.237 M

Explanation:

(A) The reaction between potassium hydrogen phthalate and barium hydroxide is:

  • 2HA + Ba(OH)₂ → BaA₂ + 2H₂O

Where A⁻ is the respective anion of the monoprotic acid (KC₈H₄O₄⁻).

We <u>convert mass of phthalate to moles</u>, using its molar mass:

  • 0.978 g ÷ 156 g/mol = 9.27x10⁻³ mol = 9.27 mmol

Now we <u>convert mmol of HA to mmol of Ba(OH)₂</u>:

  • 9.27 mmol HA * \frac{1mmolBa(OH)_{2}}{2mmolHA} = 6.64 mmol Ba(OH)₂

Finally we calculate the molarity of the Ba(OH)₂ solution:

  • 6.64 mmol / 35.8 mL = 0.129 M

(B) The reaction between Ba(OH)₂ and HCl is:

  • 2HCl + Ba(OH)₂ → BaCl₂ + 2H₂O

So<u> the moles of HCl that reacted </u>are:

  • 17.1 mL * 0.129 M * \frac{2mmolHCl}{1mmolBa(OH)_2} = 4.41 mmol HCl

And the <u>molarity of the HCl solution is</u>:

  • 4.41 mmol / 18.6 mL = 0.237 M

3 0
3 years ago
9
Svetllana [295]

Answer:

0.0025moles

Explanation:

Molarity of a solution (M) = number of moles (n) ÷ volume (V)

According to this question, to make 250 mL of a 0.01 M solution of CaCl, the following number of moles is needed:

Volume = 250mL = 250/1000 = 0.250Litres.

Using; molarity = n/V

0.01 = n/0.250

n = 0.0025

n = 2.5 × 10^-3 moles.

5 0
3 years ago
Which of the following is not an example of a subatomic particle? electron photon neutron proton
asambeis [7]
I'm pretty sure all 4 are subatomic particles but if i had to guess i'd be Photons
5 0
3 years ago
Read 2 more answers
What is the definition of quanititative observation
sukhopar [10]

Answer:

Quantitative observation is an objective collection of data which is primarily focused on numbers and values.

7 0
3 years ago
Which subatomic particle gives off visible light when it drops back down to a lower energy state?
icang [17]

Answer:

Option C = electron

Explanation:

Electrons are responsible for the production of colored light.

Electron:

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e-

Mass= 9.10938356×10⁻³¹ Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

How electrons produce the colored light:

Excitation:

When the energy is provided to the atom the electrons by absorbing the energy jump to the higher energy levels. This process is called excitation. The amount of energy absorbed by the electron is exactly equal to the energy difference of orbits.

De-excitation:

When the excited electron fall back to the lower energy levels the energy is released in the form of radiations. this energy is exactly equal to the energy difference between the orbits. The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum.

Other process may involve,

Fluorescence:

In fluorescence the energy is absorbed by the electron having shorter wavelength and high energy usually of U.V region. The process of absorbing the light occur in a very short period of time i.e. 10 ∧-15 sec. During the fluorescence the spin of electron not changed.

The electron is then de-excited by emitting the light in visible and IR region. This process of de-excitation occur in a time period of 10∧-9 sec.

Phosphorescence:

In phosphorescence the electron also goes to the excitation to the higher level by absorbing the U.V radiations. In case of Phosphorescence the transition back to the lower energy level occur very slowly and the spin pf electron also change.

5 0
3 years ago
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