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scZoUnD [109]
3 years ago
14

What is the percent of carbon-14 remaining after two half-lives?

Chemistry
1 answer:
Maslowich3 years ago
7 0
After one half-life, one half is remaining.  After two half-lives one fourth is remaining.  So that would be 25%

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Lithium and nitrogen react in a combination reaction to produce lithium nitride: 6Li(s) + N2(g) → 2Li3N(s) How many moles of lit
miss Akunina [59]

Answer:

12.5 g of Li are needed in order toproduce 0.60 moles of Li₃N

Explanation:

The reaction is:

6Li(s) + N₂(g) → 2Li₃N(s)

If nitrogen is in excess, the lithium is the limiting reactant.

Ratio is 2:6

2 moles of nitride were produced by 6 moles of Li

Then, 0.6 moles of nitride were produced by (0.6 .6)/ 2 = 1.8 moles of Li

Let's convert the moles to mass → 1.8 mol . 6.94 g/ 1mol = 12.5 g of Li

7 0
3 years ago
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When an electron in a 2p orbital of a particular atom makes a transition to the 2s orbital, a photon of approximate wavelength 6
Mariulka [41]

Answer:

The energy difference between these 2p and 2s orbitals is 3.07\times 10^{-19} J

Explanation:

Wavelength of the photon emitted = \lambda =646.3 nm =646.3\times 10^{-9} m

Energy of the photon will corresponds to the energy difference between 2p and 2s orbital = E

Energy of the photon is given by Planck's equation:

E=\frac{hc}{\lambda }

h = Planck's constant = 6.626\tiomes 10^{-34} Js

c = Speed of the light = 3\times 10^8 m/s

E=\frac{6.626\tiomes 10^{-34} Js\times 3\times 10^8 m/s}{646.3\times 10^{-9} m}

E=3.07\times 10^{-19} J

The energy difference between these 2p and 2s orbitals is 3.07\times 10^{-19} J

3 0
3 years ago
A sample of metal has a mass of 5. 2 g and absorbs 20. 0 j of energy as it is heated from 30. 0°c to 40. 0°c. What is the identi
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The identity of the metal is copper.

<h3>What is specific heat?</h3>

The amount of energy needed to raise the temperature of one gram of a substance by one degree Celsius.

Using the formula of specific heat

H = mcdT

Where, H = Heat absorbed

m = mass of the metal

c = specific heat capacity of the metal

dT = temperature change

Putting the values in the equation

20 J = 0.0052 Kg × c × ( 40.0°C - 30.0°C)

c = 20 J/0.0052 Kg × ( 40.0°C - 30.0°C)

c = 385 JKg-1°C-1

Thus, the metal is copper.

Learn more about specific heat

brainly.com/question/11297584

#SPJ4

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2 years ago
There is a gas pressure in a container that is 123kPa what is the pressure in atmospheres ?
Vera_Pavlovna [14]

Answer:

In strict SI units (highly recommended), express n in moles, R is the universal gas constant R=8.314Jmol−K , T is the temperature in Kelvins, and the volume V is in m3 . The resulting pressure P will be in Pa. R=0.082054L−atmmol−K , in which case the pressure is calculated in atm.

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