The correct answer would be B: 4.
Answer:
b. The transmittance of the cuvette must be measured in the same place each time.
Explanation:
When using a spectrophotometer, light passes not only through the liquid sample, it also passes through the cuvette. This means that each time a reading is made, you not only measure the transmittance/absorbance of the sample, <u>but of the cuvette as well</u>.
For this reason it's important that the reading of the cuvette's absorbance remains the same through all the process, so the answer is b), because different faces of the cuvette may have different absorbances.
Answer:
Amount of heat required = 2810.5 J
Explanation:
Given data:
Mass of copper = 29.2 g
Initial temperature = 25°C
Final temperature = 275°C
Amount of heat required = ?
Solution:
Specific heat capacity of copper is 0.385 j/g.°C.
Formula:
Q = m×c×ΔT
ΔT = 275°C - 25°C
ΔT = 250°C
Q = 29.2 g × 0.385 j/g.°C ×250°C
Q = 2810.5 J
Answer: The best way to promote the process are:
--> Add a bit of solid as a seed crystal.
--> Scratch the bottom of the flask gently with a stirring rod.
Explanation:
A crystal growth is seen is SUPERSATURATED solutions which contains more solute than it can normally dissolve at that given temperature. It is usually very UNSTABLE and capable of releasing the excess solute if disturbed, either by shaking or seeding with a tiny crystals.
Crystallization can be used for the separation of two salts with different solubilities as well as for purification of a soluble salt that contains insoluble solid impurities. Recrystallization improves the validity of the process. Crystallization can be initiated by:
--> Scratching the bottom of the flask gently with a stirring rod: scratching initiates crystallization by providing energy from the high-frequency vibrations.
--> Adding a bit of solid as a seed crystal: Seed crystals create a nucleation site where crystals can begin growth.
Protons goes in the blank. the word can be used for both.
