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babymother [125]

3 years ago

12

Discovered electrons have fixed amounts of energy and orbit the nucleus similar to planets? A. John dalton B. J.J. Thomson C. Er

nest Rutherford D. Niels Bohr

1 answer:

Fantom [35]3 years ago

6 0

I think is letter c thanks

You might be interested in

Formula for the compound that contains Mg2+ and O2-

jeka94

Answer:

MgO.

Explanation:

charges of both satisfy one another (balanced) -- producing a compound MgO.

7 0

3 years ago

(LO 37,45) A reaction is 75% complete in 45.0 min. How long after its start will the reaction be 50% complete if it is (A) first

seropon [69]

Answer:

A) t = 22.5 min and B) t = 29.94 min

Explanation:

Initial concentration, [A]₀ = 100

Final concentration = 100 -75 = 25

Time = 45 min

A) First order reaction

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[25] − ln[100] = - 45k

-1.386 = -45k

k = 0.0308 min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[50] − ln[100] = - 0.0308 * t

-0.693 = -0.0308 * t

t = 22.5 min

B) Zero Order

[A] = [A]₀ − kt

Using the values from the initial reaction and solving for k, we have;

25 = 100 - k(45)

-75 = -45k

k = 1.67 M min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

[A] = [A]₀ − kt

50 = 100 - (1.67)t

-50 = - 1.67t

t = 29.94 min

3 0

3 years ago

A 50.00 g sample of an unknown metal is heated to 45.00°C. It is then placed in a coffee-cup calorimeter filled with water. The

V125BC [204]

Taking into account the definition of calorimetry, the specific heat of metal is 0.165 $\frac{cal}{gC}$ .

<h3>Definition of calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where:

Q is the heat exchanged by a body of mass m.
C is the specific heat substance.
ΔT is the temperature variation.

<h3>Specific heat capacity of the metal</h3>

In this case, you know:

For metal:

Mass of metal = 50 g
Initial temperature of metal= 45 °C
Final temperature of metal= 11.08 ºC
Specific heat of metal= ?

For water:

Mass of water = 250 g
Initial temperature of water= 10 ºC
Final temperature of water= 11.08 ºC
Specific heat of water = 1.035 $\frac{cal}{gC}$

Replacing in the expression to calculate heat exchanges:

For metal: Qmetal= Specific heat of metal× 50 g× (11.08 C - 45 C)

For water: Qwater= 1.035 $\frac{cal}{gC}$ × 250 g× (11.08 C - 10 C)

If two isolated bodies or systems exchange energy in the form of heat, the quantity received by one of them is equal to the quantity transferred by the other body. That is, the total energy exchanged remains constant, it is conserved.

Then, the heat that the gold gives up will be equal to the heat that the water receives. Therefore:

- Qmetal = + Qwater

- Specific heat of metal× 50 g× (11.08 C - 45 C)= 1.035 $\frac{cal}{gC}$ × 250 g× (11.08 C - 10 C)

Solving:

- Specific heat of metal× 50 g× (-33.92 C)= 1.035 $\frac{cal}{gC}$ × 250 g× 1.08 C

Specific heat of metal× 1696 g×C= 279.45 cal

Specific heat of metal= $\frac{279.45 cal}{1696 gC}$

<u><em>Specific heat of metal= 0.165 </em></u> $\frac{cal}{gC}$

Finally, the specific heat of metal is 0.165 $\frac{cal}{gC}$ .

Learn more about calorimetry:

brainly.com/question/11586486

brainly.com/question/24724338

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brainly.com/question/24988785

#SPJ1

7 0

2 years ago

1.Give an example of a compound machine (1pt). Explain how at least two simple machines are part of this compound machine (2pts)

Law Incorporation [45]

1) An example of a compound machine could be a pair of Scissors. Their are two different simple machines in the Scissors which make up the compound machine. Both of them being a Lever, and a Fulcrum.

Hope this helps!

4 0

3 years ago

Calculate the boiling temperature of a 0.50 M solution of sucrose. Assume that the concentration is 0.50 m.

Ronch [10]

There is one missing point in the question.

The formula to find an increase in boiling Temperature is :

ΔT = kb x M

ΔT = is the increase in boiling Temperature
Kb = Boiling point constant of the Solvent
M = Molarity

You did not provide the Kb. If you have it, you just have to insert it to the formula to find the ΔT.

And assuming that the other solution is water, you just have to add it up with 100 Celcius

5 0

3 years ago