The answer is: II.The endpoint is recorded when the solution is dark red in color rather than light pink.
The endpoint is the point at which the indicator changes colour in a colourimetric titration and that is point when titration must stop.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions. If this indicator change color to dark red, more base is added and endpoint is not accurate.
If the the acid is spilled before titration, that does not make endpoint wrong and molar mass can be calculated.
In this example we can take acetic acid as carboxylic acid; basic salt sodium acetate CH₃COONa is formed from the reaction between weak acid (in this example acetic acid CH₃COOH) and strong base (in this example sodium acetate NaOH).
Balanced chemical reaction of acetic acid and sodium hydroxide:
CH₃COOH(aq) + NaOH(aq) → CH₃COONa(aq) + H₂O(l).
Neutralization is is reaction in which an acid (in this example vinegar or acetic acid CH₃COOH) and a base react quantitatively with each other.
Answer:
The correct answer is "obligatory water reabsorption in the proximal convoluted tubule".
Explanation:
The mechanism for producing concentrated urine cannot include the obligatory reabsorption of water in the proximal convoluted tubule since this process is part of the nephron, the system that filters the blood. Glucose and amino acids are reabsorbed almost entirely, as are approximately 70% of filtered potassium and 80% of bicarbonate.
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Answer:
Solid liquids , plasma gas
Explanation:
It retains its shape regardless of the shape of the container
Answer:
The system gains 126100 J
Explanation:
The heat can be calculated by the equation:
Q = nxCxΔT, where Q is the heat, C is the heat capacity,n is the number of moles and ΔT is the variation of temperature (final - initial). The number of moles is the mass divided by the molar mass, so:
n = 250/4 = 62.5 mol.
The system must be in thermal equilibrium with the surroundings, so if the temperature of the surroundings decreased 97 K, the temperature of the system increased by 97 K, so ΔT = 97 K
Q = 62.5x20.8x97
Q = 126100 J
Answer:
A chemical bond is defined as the force which helps to bind more than two atoms in a molecule. There are different types of chemical bonding are present in molecules such as:
1) Ionic bonding: Because of the transfer of electrons it is present in ionic compounds. BaS is an example of ionic bonding which is containing some covalent character.
2) Covenant bonding: Because of the sharing of electrons it forms molecules. Rubber is the example of covalent bonding with some van der walls.
3) Metallic bonding: In the free state it is present in atoms of metal such as Brass is a good example of a metallic bonding because it is a metal alloy.
4) Van der walls bonding: In atoms, It includes repulsion and attraction. Solid xenon is the example of Van der wall bonding because it is an inert gas.
