Answer:
23 and 56 minutes or 24 hours
Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to other, distant, stars. Earth's rotation is slowing slightly with time; thus, a day was shorter in the past
Complete question :
A jeweler has five rings, each weighing 18 g, made of an alloy of 10% silver and 90% gold. She decides to melt down the rings and add enough silver to reduce the gold content to 75%. How much silver should she add?
Answer:
Kindly check explanation
Explanation:
Given the following :
Weight of each alloy = 18g
Initial % of Silver = 10% = 0.1
Initial % of Gold = 90% = 0.9
New % of gold = 75% = 0.75
Hence, new % of silver will be (1 - 0.75) = 0.25
Let the amount of silver to be added = s
Hence,
Initial gold content = final gold content + added silver
18 * 0.9 = 0.75(18 + s)
16.2 = 13.5 + 0.75s
16. 2 = 13.5 + 0.75s
16.2 - 13.5 = 0.75s
2.7 = 0.75s
s = 2.7 / 0.75
s = 3.6
S = 3.6
Hence the amount of silver needed per ring in other to reduce the gold content = 3.6g
Total for the 5 rings = (3.6 * 5) = 18g
I think they test ideas about chemical evolution by doing experiments. Hope this helps
Answer:
- <em>The net ionic equation is: </em><u>Ag⁺ (aq) + Cl ⁻ (aq) → AgCl (s)</u>
Explanation:
<u>1) Start by writing the total ionic equation:</u>
The total ionic equation shows each aqueous substance in its ionized form, while the solid or liquid substances are shown with their chemical formula.
These are the ionic species:
- AgF (aq) → Ag⁺ (aq) + F⁻ (aq)
- NH₄Cl (aq) → NH₄⁺ (aq) + Cl ⁻ (aq)
- NH₄F(aq) → NH₄⁺ (aq) + F⁻ (aq)
Then, replace each chemical formula in the chemical equation by those ionic forms:
- Ag⁺ (aq) + F⁻ (aq) + NH₄⁺ (aq) + Cl ⁻ (aq) → AgCl (s) + NH₄⁺ (aq) + F⁻ (aq)
That is the total ionic equation.
<u>2) Spectator ions:</u>
The ions that appear in both the reactant side and the product side are considered spectator ions (they do not change), and so they are canceled.
In our total ionic equation they are F⁻ (aq) and NH₄⁺ (aq).
After canceling them, you get the net ionic equation:
<u>3) Net ionic equation:</u>
- Ag⁺ (aq) + Cl ⁻ (aq) → AgCl (s) ← answer
