Answer:
(D) (CH3CH2)2NH
Explanation:
In order to decide which base is strongest we need to calculate its PKb
PKb = -log [Kb]
A large Kb value and small PKb value gives the strongest base
Compound Kb PKb
(A) C6H5NH2 - 4 x 10^-10 9.349
(B) NH3 1.76x 10^-5 4.754
(C) CH3NH2 4.4x 10^-4 3.357
(D) (CH3CH2)2NH 8.6x 10^-4 3.066
(E) C5H5N 1.7x10^-9 8.77
Clearly (CH3CH2)2NH is the strongest base.
The unbalanced equation is BF3 + Li2 SO3 --> B2 (SO3)3 + LiF, where the numbers to the right of the symbols are subscripts. The balanced equation is 2 BF3 + 3 Li2SO3 ---> B2 (SO3)3 + 6LiF. The numbers in front of every formula (compound) are the respective coefficients. You can check that the equation is balanced counting every element: There are 2B in the side of the reactants and 2B in the side of the products; there are 6F in the side of the reactants and 6F in the side of the products; there are 6 Li in the side of the reactants and 6 Li in the side of the products; and there are 3 SO3 in the side of the reactants and 3 SO3 in the side of the products. <span>So, the coefficient of the LiF is 6.</span>
Chemical properties of matter can only be observed and measured by performing a chemical change.
- Density and boiling are not chemical changes.
- This leaves reactivity and combustion. Reactivity does not need to be observed at STP so the statement is wrong.
Combustion is the best answer.
Tijuan mixed a solid and a liquid together in a beaker. He determined that a chemical change occurred. ... After a week, he observed that only solid salt remained in the cup and the mass had decreased I hope this helped! In some way