Answer:
E = 3.81×10 ⁻²¹ J
Explanation:
Given data:
Frequency of photon = 5.75 ×10¹² Hz
Plancks constant = 6.626 ×10⁻³⁴ Js
Energy of photon = ?
Solution:
E = h×f
E = 6.626 ×10⁻³⁴ Js × 5.75 ×10¹² s⁻¹
E = 38.1×10 ⁻²² J
E = 3.81×10 ⁻²¹ J
To measure the mass of a given powdered substance do the following:
1. Zero the weighing balance, that is, put the weigh balance at zero mark.
2. Put an empty weighing paper on the balance and take its reading. Record it as X1.
3. Use spatula to put the powder you want to measure on the weighing paper on the balance. Take your reading and record it as X2.
The mass of the powered is X2 - X1.
Answer:
More exactly this number is 6.02 x 1023 10 2 3 .
<h3>Answer:</h3>
2.55 × 10²² Na Atoms
<h3>Solution:</h3>
Data Given:
M.Mass of Na = 23 g.mol⁻¹
Mass of Na = 973 mg = 0.973 g
# of Na Atoms = ??
Step 1: Calculate Moles of Na as:
Moles = Mass ÷ M.Mass
Moles = 0.973 g ÷ 23 g.mol⁻¹
Moles = 0.0423 mol
Step 2: Calculate No, of Na Atoms as:
As 1 mole of sodium atoms counts 6.022 × 10²³ and equals exactly to the mass of 23 g. So, we can write,
Moles = No. of Na Atoms ÷ 6.022 × 10²³ Na Atoms.mol⁻¹
Solving for No. of Na Atoms,
No. of Na Atoms = Moles × 6.022 × 10²³ Na Atoms.mol⁻¹
No. of Na Atoms = 0.0423 mol × 6.022 × 10²³ Na Atoms.mol⁻¹
No. of Na Atoms = 2.55 × 10²² Na Atoms
<h3>Conclusion: </h3>
2.55 × 10²² sodium atoms are required to reach a total mass of 973 mg in a substance of pure sodium.
