Hey there!
The acronym STP in chemistry stands for Standard Temperature and Pressure. At STP, the temperature will be 273.15 Kelvin (0°C or 32°F) and one mole of gas will occupy 22.4 liters of volume. Standard pressure is set at 1 atm. STP measurements are often used to solve the ideal gas formula (PV = nRT).
Hope this helped you out! :-)
The correct answer is:
D) a chemical change produces a new substance by breaking and forming new bonds
Answer:
Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen.
Explanation:
The work is to calculate the molar mass of the solute (adrenaline) from the elevation of the boling point and compare with the mass of the structural formula. If they both are reasonably equal then you conclude that the results are in agreement, else they are not in agreement.
Since, you did not include the structural formula, I can explain the whole procedure to calculate the molar mass from the boiling point elevation, and then you can compare with the mass of the structural formula that only you know.
Determination of the molar mass from the boiling point elevation.
1) With the elevation of the boiling point, which is a colligative property, you can find the molality of the solution, using the formula:
ΔTb = i * Kb * m
Where:
> ΔTb is the increase of the boiling point of ths solvent, i.e. CCl4.
> i van't Hoff constant = 1 (because the solute is non ionic)
> m is the molality of the solution
2) Clearing m you get:
m = ΔTb / Kb
Kb is a datum that you must find in a table of internet (since the statement does not include it).
I found Kb = 5.02 °C/m
Then, m = 0.49°C / (5.02°C/m) = 0.09760956 m
3) With m and the mass of solvent you find the number of moles of solute using the formula:
m = number of moles of solute / kg of solvent
You have the mass of the solvent = 36.0 g = 0.0360 kg, so you can solve for the number of moles of solute:
=> number of moles of solute = m * kg of solvent = 0.09760956 m * 0.036kg = 0.0035139 moles
4) With the nuimber of moles and the mass you find the molar mass:
molar mass = mass in grams / number of moles = 0.64 g / 0.0035139 moles = 182 g/mol <------------- this is the important result
5) Now that you have the molar mass you can compare with the mass of the molecular formula. If they are reasonably equal then you conclude that the <span>molar mass of adrenaline calculated from the boiling point elevation is in agreement with the structural formula</span>
Carboxylic acids: considered as weak acids due to they ionize in solution to give -COO⁻ and H⁺, they are abundant in nature, they can form intermolecular hydrogen bonds so they exist as dimers (remember that alcohols also can form hydrogen bonds).
- Acids have higher boiling and melting points than corresponding molar mass compounds due to the formation of hydrogen bond
- Aromatic carboxylic acids are solids in nature at room temperature