HELP PLEASE!!!!!!!

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

5. How many moles are equal to 2.4 x 1023 formula units of sodium chloride?

Zepler [3.9K]

Answer:

<h3>The answer is 0.4 moles</h3>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

$n = \frac{N}{L} \\$

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

$n = \frac{2.4 \times {10}^{23} }{6.02 \times {10}^{23} } = \frac{2.4}{6.02} \\ = 0.398671096....$

We have the final answer as

<h3>0.4 moles</h3>

Hope this helps you

7 0

3 years ago

Write the half-reactions as they occur at each electrode and the net cell reaction for this electrochemical cell containing indi

AlexFokin [52]

Explanation:

The given cell reaction is as follows.

$In(s)| In^{3+}(aq) || Cd^{2+}(aq) | Cd(s)$

Hence, reactions taking place at the cathode and anode are as follows.

At anode ; Oxidation-half reaction : $In(s) \rightarrow In^{3+}(aq) + 3e^{-}$ ...... (1)

At cathode; Reduction-half reaction : $Cd^{2+}(aq) + 2e^{-} \rightarrow Cd(s)$ ....... (2)

Hence, balance the half reactions by multiplying equation (1) by 2 and equation (2) by 3.

Therefore, net cell reaction is as follows.

$2In(s) \rightarrow 2In^{3+}(aq) + 6e^{-}$

$3Cd^{2+}(aq) + 6e^{-} \rightarrow 3Cd(s)$

Net reaction: $2In(s) + 3Cd^{2+}(aq) \rightarrow 2In^{3+}(aq) + 3Cd(s)$

Thus, we can conclude that the overall cell reaction is as follows.

$2In(s) + 3Cd^{2+}(aq) \rightarrow 2In^{3+}(aq) + 3Cd(s)$

4 0

3 years ago

Identify the classification of milk. group of answer choices aerosol solid aerosol foam emulsion solid emulsion

kotykmax [81]

Milk is an example of solid emulsion. Hence, option D is correct.

<h3>What is emulsion?</h3>

An emulsion is defined as a colloid consisting of two or more non-homogenous type of liquids in which one of the liquid contains the dispersion of the different form of liquids.

Emulsion consist of a dispersion of two liquids that are immiscible with each other.

One of the liquids act as the dispersion medium and the other will act as the dispersed phase.

Emulsions are colloids in which both the dispersed phase and dispersion medium are liquids.

Types of Emulsion:

Oil in water (O/W)

In this type of emulsion, the oil will be the dispersed phase and water will be the dispersion medium.
Example of o/w emulsion is milk.

2. Water in oil (W/O)

In this type, water will be the dispersed phase and oil will be the dispersion medium.
Margarine is an example of water in oil emulsion.

Milk is an example of solid emulsion. Hence, option D is correct.

Learn more about emulsion, Here:

brainly.com/question/6677364

#SPJ4

4 0

2 years ago

Identify the state of matter in between C&D.

ladessa [460]

Answer:

Here's the answer in order

A

B

C

A

D

A

C

D

Explanation:

lol nvm

6 0

3 years ago