The first reason to repeat experiments is simply to verify results. Different science disciplines have different criteria for determining what good results are. Biological assays, for example must be done in at least triplicate to generate acceptable data. Science is built on the assumption that published experimental protocols are repeatable.
2) The next reason to repeat experiments is to develop skills necessary to extend established methods and develop new experiments. “Practice make perfect” is true for the concert hall and the chemical laboratory.
3) Refining experimental observations is another reason to repeat. Maybe you did not follow the progress of the reaction like you should have.
4) Another reason to repeat experiments is to study and/or improve them in way. In the synthetic chemistry laboratory, for example, there is always a desire to improve the yield of a synthetic step. Will certain changes in the experimental conditions lead to a better yield? The only way to find out is to try it! The scientific method informs us that it is best to only make one change at a time.
5) The final reason to repeat an extraction, chromatographic or synthetic protocol is to produce more of your target substance. This is sometimes referred to scale-up.
Answer : When we consider the atmospheric pressure as 1 atm then according to the ideal gas equation we can find out the molar mass of any unknown by this formula ;
PV=nRT
so if the pressure increases than 1 atm then we can see from the above equation that it will result in greater value for the number of moles (n) in the above equation.
While n = m/M where m is mass of the unknown in g and M is molecular mass.
So, if pressure is higher then it will result in molar mass of unknown which is much smaller.
Answer:
B. a change in their state or substance
Explanation:
A change of state consists of a physical process in which the structure of the substance changes, its appearance. EXAMPLE: in the merger, the solid state becomes liquid, changes the rearrangement of particles from being highly compacted to being less compact.
Answer:
Explanation:
a) : This is a non polar covalent compound which are held by weak vanderwaal forces of attraction.
b) : This is a covalent compound which is polar due to the presence of lone pair of electrons and are held by dipole-dipole forces of attraction.
c) : These are joined by a special type of dipole dipole attraction called as hydrogen bond. It forms between electronegative nitrogen atom and hydrogen atom and is the strongest interaction.
d) : This is a covalent compound and is non polar which are held by weak vanderwaal forces of attraction.
e) : This is a covalent compound and is non polar which are held by weak vander waal forces of attraction.
Answer:The lone pair of electrons takes up more space than a regular bonding pair since it it is not confined to be between two atoms, so it adds coulombic repulsion to the bonding pairs and compresses the angle. Therefore, the bond angle is less than the standard 109.5∘ . It is actually 97.7∘