______ is the type of heat that roasts the marshmallows.

How could you engineer a device that produces beneficial friction and heat?

nlexa [21]

Answer:

Hi

Explanation:

That's why rubbing your hands together makes them warmer. ... Friction causes the molecules on rubbing surfaces to move faster, so they have more energy. This gives them a higher temperature, and they feel warmer. Heat from friction can be useful.

3 0

3 years ago

What mass in grams would 5.7L of hydrogen gas occupy at STP?

tekilochka [14]

Answer: The correct answer is: " 0.54 g " .

__________________________________________

Explanation:

Note that "hydrogen gas" is:

H₂ (g) ; that is: a "diatomic element" (diatomic gas) ;

_________________________________________

The molecular weight of "H" is: 1.00794 g ;

(From the Periodic Table of Elements).

So, the molecular weight of: H₂ (g) is:

" 1.00794 g * 2 = 2.01588 g ; {use calculator) ;

_________________________________________

Note the conversion for a gas at STP:

______

1 mol of a gas = 22.4 L gas;

___

i.e. " 1 mol / 22.4 L " ;

____

So: " 5.7 L H₂ (g) $* \frac{1 mol H_{2} }{22.4 L} *\frac{2.01588 g}{mol} =? ;$

The "L" ("literes" cancel out to "1" ; since "L/L = 1 ;

The "mol" (moles) cancel out to "1" ; since "mol/mol = 1 ;

____

and we are left with:

____

[5.7 * 2.104588 g ] / 22.4 = ? g ;

______________________

→ [ 11.9961516 g ] / 22.4 =

0.53554248214 g ;l

_____________________________

We round this value to: " 0.54 g " ;

→ since "5.7 L " has 2 (two) significant figures;

22.4 is an exact number conversion;

and "5.7 L" has fewer significant figures than:

" 2.104588 " ; or: " 1.00794 " .

→ as such: We round to "2 (two) significant figures."

______________________________

Hope this is helpful. Wishing you the best in your academic endeavors!

_______________________________

8 0

3 years ago

An iron bar of mass 841 g cools from 84°C to 7°C. Calculate the heat released (in kilojoules) by the metal.

Oduvanchick [21]

Answer:

28.75211 kj

Explanation:

Given data:

Mass of iron bar = 841 g

Initial temperature = 84°C

Final temperature = 7°C

Heat released = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

specific heat capacity of iron is 0.444 j/g.°C

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 7°C - 84°C

ΔT = -77°C

By putting values,

Q = 841 g × 0.444 j/g.°C × -77°C

Q = 28752.11 j

In Kj:

28752.11 j × 1 kJ / 1000 J

28.75211 kj

8 0

3 years ago

Here's the question ~

Lelechka [254]

Using the Rydberg formula, the spectral line of H - atom is suitable for this purpose is Paschen, ∞ → 3.

Using the Rydberg formula;

1/λ = RH(1/nf^2 - 1/ni^2)

Given that;

λ = wavelength

RH = Rydberg constant

nf = final state

ni = initial state

When final state = 3 and initial state = ∞

Then;

1/λ = 1 × 10^7 m-1 (1/3^2 - 1/ ∞^2)

1/λ = 1 × 10^7 m-1 (1/3^2 )

λ = 900 nm

Hence, the correct answer is Paschen, ∞ → 3

Learn more about the Rydberg formula; brainly.com/question/17753747

3 0

2 years ago

Read 2 more answers

What is a change that will not affect the pressure in a container ? A.increasing the volume of the fluid B . Changing the materi

ExtremeBDS [4]

Answer:

B . Changing the material that the fluids container is made of

Explanation:

Changing the material of the container does not affect the pressure in a container whereas increasing the volume, changing the weight of the fluid, and heating/cooling the fluid will all change the pressure.

4 0

3 years ago