3 first significant figure
6 second significant figure
5 third significant figure
4 cannot exceed 5, so retain 5 instead of increasing it to 6
0.0365
Answer:
When HBCG and BCG^- are at the same concentration, the resulting color is green. This green shade initially becomes visible at a pH of 3.8.
Explanation:
HBCG serves as an indicator formed by dissolving solids in ethanol.
Since
Ka=[BCG−][H3O+][HBCG] When [BCG-] equals [HBCG], it follows that Ka = [H3O+].
<pWith a pH of 3.8,<pKa= [H3O+] = -antilog pH = -antilog (3.8)
Ka= 1.58 ×10^-4
The element with atomic number 58 is Cerium, meaning its symbol should be Ce rather than Co, which belongs to Cobalt with atomic number 27. Therefore, the notation for isotopes consists of the element's symbol accompanied by a superscript and a subscript, properly aligned. The superscript indicates the mass number.
Mass number = protons + neutrons = 58 + 33 = 91
The subscript denotes the atomic number, which is 58. This notation is illustrated in the attached image.
The molar mass of C2F4 (tetrafluoroethylene) is 100 g/mol. To find the number of moles of C2F4 in the specified quantity,
n = (5.85 g) / (100 g/mol) = 0.0585 mols C2F4
The calculation for the number of molecules per mole is done via the equation,
(0.0585 mols) x (6.022 x 10^23)
Given that each molecule contains 4 F atoms, then,
(0.0585 mols) x (6.022 x 10^23)(4)
= 1.41 x 10^23 atoms of F