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3 years ago

How many protons, electrons, and neutrons are in calcium?

Chemistry

1 answer:

noname [10]3 years ago

3 0

Answer:

20 protons , 20 electrons and 20 neutrons

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Carbon 14 has a half-life of 5730 years. A geologist has dated a fossil sample, at roughly 28650 years. How much carbon 14 remai

IgorC [24]

<h3>Answer </h3>

After another 5730 years ( three half lives or 17190 years) 17.5 /2 = 8.75mg decays and 8.75g remains left. after three half lives or 17190 years, 8.75 g of C-14 will be

Explanation:

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3 years ago

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TiliK225 [7]

Answer:

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Explanation:

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A silver ring has a mass of 138.45 g. how many calories of heat are required to increase the temperature from 11.8 c to 162.5 c?

garik1379 [7]

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3 years ago

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Calculate the tempature of a 0.50 mol sample of a gas at a pressure of 0.987 atm and a volume of 12 L

dalvyx [7]

Answer:

The temperature is 288, 88K

Explanation:

We use the formula PV= nRT:

T= PV/nR

T= 0,987 atm x12 L/0,50 mol x 0,082 l atm/K mol

6 0

3 years ago

The rate constant k for a certain reaction is measured at two different temperatures temperature 376.0 °c 4.8 x 108 280.0 °C 2.3

9966 [12]

Answer:

The activation energy for this reaction = 23 kJ/mol.

Explanation:

Using the expression,

$\ln \dfrac{k_{1}}{k_{2}} =-\dfrac{E_{a}}{R} \left (\dfrac{1}{T_1}-\dfrac{1}{T_2} \right )$

Where,

$k_1\ is\ the\ rate\ constant\ at\ T_1$

$k_2\ is\ the\ rate\ constant\ at\ T_2$

$E_a$ is the activation energy

R is Gas constant having value = 8.314×10⁻³ kJ / K mol

$k_2=2.3\times 10^8$

$T_2=280\ ^0C$

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T = (280 + 273.15) K = 553.15 K

$T_2=553.15\ K$

$k_1=4.8\times 10^8$

$T_1=376\ ^0C$

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T = (376 + 273.15) K = 649.15 K

$T_1=649.15\ K$

So,

$\left(\ln \left(\:\frac{4.8\times \:\:\:10^8}{2.3\times \:\:\:10^8}\right)\right)\:=-\frac{E_a}{8.314\times \:10^{-3}\ kJ/mol.K}\times \:\left(\frac{1}{649.15\ K}-\frac{1}{553.15\ K}\right)$

$E_a=-\frac{10^{-3}\times \:8.314\ln \left(\frac{10^8\times \:4.8}{10^8\times \:2.3}\right)}{-\frac{96}{359077.3225}}\ kJ/mol$

$E_a=-\frac{\frac{8.314\ln \left(\frac{4.8}{2.3}\right)}{1000}}{-\frac{96}{359077.3225}}\ kJ/mol$

$E_a=22.87\ kJ/mol$

<u>The activation energy for this reaction = 23 kJ/mol.</u>

6 0

3 years ago