Answer:
The percent recovery from re crystallization for both compounds A and B is 69.745 and 81.44 % respectively.
Explanation:
Mass of compound A in a mixture = 119 mg
Mass of compound A after re-crystallization = 83 mg
Percent recovery from re-crystallization :

Percent recovery of compound A:

Mass of compound B in a mixture = 97 mg
Mass of compound B after re-crystallization = 79 mg
Percent recovery of compound B:

Molar mass is the mass of one stable molecule of a compound, that cannot join with another molecule of the same kind to form a new one, while an empirical formula is the molecular formula in its simplest form. E.g. empirical formula of ethene is CH2while its molecular formula is C2H4.
Answer:
A) covalent bond
Explanation:
Covalent bonding generally happens between nonmetals.
Answer:
Indicators show changes in the pH of a solution
Explanation:
A pH meter is an instrument that measures the hydrogen-ion activity in aqueous solutions, indicating the acidity or alkalinity of the solution expressed as pH .The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, hence the pH meter is sometimes referred to as a potentiometric pH meter. Potentiometric pH meters measure the voltage between two electrodes and display the result converted into the corresponding pH value. The instrument comprises of a simple electronic amplifier and a pair of electrodes, or alternatively a combination electrode, and some form of display calibrated in pH units. It usually has a glass electrode and a reference electrode, or a combination electrode. The electrodes, or probes, are inserted into the solution to be tested.
Organic indicators are chemical species that change their colour in response to changes in the pH of the solution. This implies that the anionic and protonated forms of the indicator possess different colours. Hence the colour changes in acidic, basic and neutral solutions. The images attached indicate the colour changes in phenolphthalein and methyl orange in acidic and basic media accordingly.
A solute dissolves in excess solvent to form a solution:
solute + solvent → solution
<h3>What is the Enthalpy and their relation ? </h3>
A thermodynamic system's enthalpy, which is one of its properties, is calculated by adding the system's internal energy to the product of its pressure and volume. It is a state function that is frequently employed in measurements of chemical, biological, and physical systems at constant pressure, which the sizable surrounding environment conveniently provides.
A solution is a uniform mixture of two or more components that can exist in the solid, liquid, or gas phases. The amount of heat that is released or absorbed during the dissolving process is known as the enthalpy change of solution (at constant pressure).
There are two possible values for this enthalpy of solution ( H solution ) : positive (endothermic) and negative (exothermic). It is most straightforward to visualize a hypothetical three-step process occurring between two substances while trying to grasp the enthalpy of solution. The solute is one substance; let's call it A. The solvent is the second component; let's call it B.
The initial procedure exclusively affects the solute A and calls for disabling all intramolecular forces holding it together. This indicates that the molecules of the solute separate. This process' enthalpy is known as H1. Since breaking interactions requires energy, this is always an endothermic process, hence H1>0.
Their sign will be opposite.
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