Answer:
4121 years
Explanation:
From;
0.693/t1/2 = 2.303/t log No/N
t1/2= half life of the carbon-14
No= count rate of the living tissue
N= count rate of the sample
t = age of the sample
0.693/5730 =2.303/t log (13.5/8.2)
1.21 * 10^-4 = 2.303/t * 0.2165
1.21 * 10^-4 = 0.4986/t
t = 0.4986/1.21 * 10^-4
t = 4121 years
Answer:
B. A rate constant
Explanation:
The mathematical expression of rate law is given below,
Rate = K[A]m[B]n
This rate law show the relationship between the rate of chemical reaction and concentration of reactants.
In given equation [A] and [B] are molar concentration of reactants while K represent rate constant.
The value of K is specific for particular reaction at particular temperature,
m and n are represent exponents and determine experimentally. The value of K is not depend upon the concentrations of reactant but depend upon the surface area and temperature
Answer:
[H₃O⁺] = 6.31 x 10⁻³ M.
Explanation:
- To find the hydronium ion concentration [H₃O⁺], we can use the relation:
<em>pH = - log[H₃O⁺].</em>
<em></em>
∴ 2.2 = - log[H₃O⁺].
∴ log[H₃O⁺] = - 2.2
<em>∴ [H₃O⁺] = 6.31 x 10⁻³ M.</em>
The paper being torn in half or folding it
Answer:
The correct option is;
D)
Explanation:
The given reaction is presented as follows;
NH₄Cl (s) → NH₃ (g) + HCl (g) ΔH° = 176 kJ/mol, ΔS° = 0.285 kJ/(mol·K)
We note that the Gibbs free energy, ΔG° is represented by the following equation;
ΔG° = ΔH° - T·ΔS°
Where:
T = Temperature (Kelvin)
The reaction will be spontaneous for exergonic reactions, ΔG° < 0 and it will not be spontaneous for endergonic reaction, ΔG° > 0
At room temperature, T = 25 + 273.15 = 298.15 K
Which gives;
ΔG° = 176 - 298.15 × 0.285 = 91.03 kJ/mol which is > 0 Not spontaneous reaction
At 800°C, we have;
T = 273.15 + 800°C + 1073.15 K
ΔG° = 176 - 1073.15 * 0.285 = -129.85 kJ/mol which is < 0 the reaction will be spontaneous
The correct option is therefore, that at room temperature, the reaction is not spontaneous. However, at high temperatures. like 800 °C, the free energy value turns negative and this reaction becomes spontaneous.
