on the periodic table each element has a symbol. which of the following is the symbol for nitrogen? a. ni b. na c. nd d. n

A sample of wood from the remains of a ship was found to contain 40.0% of C-14 as of ordinary wood found now. If the half-life p

kondaur [170]

Answer:

7628 y

Explanation:

Carbon-14 is radioactive and it follows the first-order kinetics for a radioactive decay. The first-order kinetics may be described by the following integrated rate law:

$ln(\frac{[A]_t}{[A]_o})=-kt$

Here:

$[A]_t$ is the mass, moles, molarity or percentage of the material left at some time of interest t;

$[A]_o$ is the mass, moles, molarity or percentage of the material initially, we know that initially we expect to have 100 % of carbon-14 before it starts to decay;

$k = \frac{ln(2)}{T_{\frac{1}{2}}}$ is the rate constant;

$t$ is time.

The equation becomes:

$ln(\frac{[A]_t}{[A]_o})=-\frac{ln(2)}{T_{\frac{1}{2}}}t$

Given:

$\frac{[A]_t}{[A]_o} = \frac{40.0 %}{100.0 %}$

$T_{\frac{1}{2}} = 5770 y$

Solve for time:

$t = -\frac{ln(\frac{[A]_t}{[A]_o})\cdot T_{\frac{1}{2}}}{ln(2)}$

In this case:

$t = -\frac{ln(\frac{40.0\%}{100.0\%})\cdot 5770 y}{ln(2)}$

$t = 7628 y$

3 0

3 years ago

What is the mass of 0.80 moles of Mg? (1 point)

Aneli [31]

Answer:

m = 19 grams

Explanation:

Given that,

No. of moles, n = 0.8

The molar mass of magnesium, M = 24.305 u

We need to find the mass of 0.80 moles of Mg. We know that given mass to the molar mass is equal to no of moles. Let the mass is m. So,

$n=\dfrac{m}{M}\\\\m=n\times M\\\\m=0.8\times 24.305 \\\\m=19.444\ \text{grams}$

or

m = 19 grams

So, the mass of 0.8 moles of Mg is 19 grams.

6 0

3 years ago

Whats the formula for lithium nitride

Brrunno [24]

Answer:

Lithium nitride. Trilithium nitride. 26134-62-3. Lithium nitride (Li3N) Li3N.

4 0

3 years ago

Which concept describes the formation of four equivalent, single, covalent bonds by carbon in its compounds that resembles metha

Montano1993 [528]

Carbon is special and unique because it is able to form different compounds with a lot of elements, including itself. When it bonds with itself, this is possible because of the concept of hybridization. It is the mixing of atomic orbitals into a new hybrid orbital. In this case, methane is formed through the sp³ hybridization.

4 0

3 years ago

Balance the following redox equation in acidic solution using the smallest integers possible and select the correct coefficient

romanna [79]

Answer:

Coefficient of $H^{+}(aq)$ is more than 4

Explanation:

Oxidation: $Sn^{2+}(aq)\rightarrow Sn^{4+}(aq)$

Balance charge: $Sn^{2+}(aq)-2e^{-}\rightarrow Sn^{4+}(aq)$ ......(1)

Reduction: $Cr_{2}O_{7}^{2-}(aq)\rightarrow Cr^{3+}(aq)$

Balance Cr: $Cr_{2}O_{7}^{2-}(aq)\rightarrow 2Cr^{3+}(aq)$
Balance O and H in acidic medium: $Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)\rightarrow 2Cr^{3+}(aq)+7H_{2}O(l)$
Balance charge: $Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)+6e^{-}\rightarrow 2Cr^{3+}(aq)+7H_{2}O(l)$ .......(2)

$[3\times Equation-(1)]+Equation(2)$ gives balanced equation:

$3Sn^{2+}(aq)+Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)\rightarrow 3Sn^{4+}(aq)+2Cr^{3+}(aq)+7H_{2}O(l)$

So coefficient of $H^{+}(aq)$ is more than 4

3 0

3 years ago