Answer:
52 da
Step-by-step explanation:
Whenever a question asks you, "How long to reach a certain concentration?" or something similar, you must use the appropriate integrated rate law expression.
The i<em>ntegrated rate law for a first-order reaction </em>is
ln([A₀]/[A] ) = kt
Data:
[A]₀ = 750 mg
[A] = 68 mg
t_ ½ = 15 da
Step 1. Calculate the value of the rate constant.
t_½ = ln2/k Multiply each side by k
kt_½ = ln2 Divide each side by t_½
k = ln2/t_½
= ln2/15
= 0.0462 da⁻¹
Step 2. Calculate the time
ln(750/68) = 0.0462t
ln11.0 = 0.0462t
2.40 = 0.0462t Divide each side by 0.0462
t = 52 da
One chemical property of water is that it can melt many substances.
Answer:
Explanation:
Ions which will be definitely absent -
Ag⁺ , Hg₂⁺ , Pb⁺², because their chlorides are insoluble in water.
Ba⁺² ,Ca⁺² because their carbonates are insoluble in water,
Ions which will be definitely present
Cu⁺² , Pb⁺² . Hg⁺² , Sb⁺³ , Sn⁺² , because their sulphides are insoluble at pH = 8.
For the rest nothing can be said.
Answer:
4 valence electrons
Despite the fact that the word silicon has a ubiquitous affiliation with all things electronic, Si itself is not a good electrical conductor. It has 4 valence electrons, meaning that filling its outer shell it can form a very strong lattice with 4 neighboring Si atoms-with no un-bonded electrons remaining
