How do you reduce a 90% gold content into 75%

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In summary, the conversation discusses melting 5 gold rings weighing 18 grams each and adding silver to make a 75% gold alloy. The equation presented is incorrect and the correct formula for the total mass and percentage of gold in the alloy is discussed. It is noted that turning more gold into less is not the intention, but rather turning more gold into a more useful alloy. The conversation also clarifies that this is not a homework question and there is no intent to deceive.
  • #1
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The title says it all.

Say you have 5 rings, each weighing 18 grams (10% alloy and 90% gold).
If you would melt them all and add silver to make it 75% gold,

1) how much silver do you have to add?

2) Does melting 5 rings with 18grams each give 90 grams in total?

3) is this equation to solve for this problem right?

let x = amount of silver to add
total grams = 90 g

total grams (.90) + x silver (100%) = total grams + x (.75)
90(.9) + 1x = 90(.75)
81 + x = 67.5 + .75x
x = -54

4) Am I doing/thinking them all wrong?

thanks.
 
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  • #2
This is a homework type question, I am moving it to HW forum.

You are right about total mass of gold being 90 g, but this equation

acen_gr said:
total grams (.90) + x silver (100%) = total grams + x (.75)

is wrong (and to be honest I am not even able to decipher what you tried to do).

Let's assume (like you nicely did), that you added x g of silver.

If so, what is the formula for the total mass of the alloy?

What is the formula for the percentage of gold in this alloy?
 
  • #3
more importantly, why do you want to turn more gold to less? That stuff is more expensive than silver anyway
 
  • #4
Woopydalan said:
more importantly, why do you want to turn more gold to less? That stuff is more expensive than silver anyway

He is not wanting to turn more into less; he is wanting to turn more into even more.

Starting with x gram of gold and y gram of other stuff to make (x + y) gram of "gold" (90%), he wants to add z gram of other stuff to make (x + y + z) gram of "gold" (75%).

And no, even if it is not a homework question, he is not likely to be pulling a swindle. 75% gold is 18 carat gold, which is a much more useful material for certain purposes than pure gold.
 
  • #5


I would approach this problem using the principles of conservation of mass and stoichiometry. The first step would be to calculate the amount of gold present in the 5 rings:

Gold content = 5 rings x 18 grams/ring x 0.90 (90% gold) = 81 grams

Next, we need to determine the amount of silver that needs to be added to reduce the gold content from 90% to 75%. This can be done by setting up a proportion:

(81 grams gold / total grams) = (75% / 100%)

Solving for total grams, we get:

Total grams = 81 grams gold / 0.75 = 108 grams

Since we started with 90 grams of gold, we need to add 18 grams of silver (108 grams - 90 grams = 18 grams) to achieve a 75% gold content.

To answer your specific questions:

1) We need to add 18 grams of silver to reduce the gold content from 90% to 75%.

2) Yes, melting 5 rings with 18 grams each would give a total of 90 grams.

3) Your equation is correct, but the value for x is incorrect. It should be 18 grams, not -54 grams.

4) You are on the right track, but it is important to use the correct values and units in your calculations. It is also helpful to clearly define your variables and show all steps in your calculations.

I hope this helps!
 

1. How do you calculate the amount of gold needed to reduce 90% gold content into 75%?

To calculate the amount of gold needed, you will first need to determine the total weight of the gold. Then, using the percentage of gold you want to achieve (75%), you can calculate the weight of gold needed by multiplying the total weight by 0.75. This will give you the amount of gold needed to achieve 75% gold content.

2. What is the process for reducing the gold content?

The process for reducing the gold content involves mixing the gold with a metal of lower karat (such as copper or silver) in a specific ratio. This will result in a new alloy with a lower gold content. The exact process may vary depending on the specific gold content and desired percentage.

3. Is it possible to reduce the gold content without losing any of the gold?

No, it is not possible to reduce the gold content without losing some of the gold. The process of reducing the gold content involves mixing it with another metal, which will result in some of the gold being replaced by the other metal. However, the loss of gold can be minimized by careful measurement and mixing.

4. Can the reduced gold content be reversed back to its original 90%?

Yes, it is possible to reverse the reduced gold content back to its original 90%. This would involve separating the gold from the other metal in the alloy and then adding more gold to achieve the desired percentage. However, this process may not be cost-effective and may result in some loss of gold.

5. Are there any precautions to take when reducing gold content?

Yes, there are certain precautions that should be taken when reducing gold content. This includes using appropriate safety gear and following proper mixing ratios to avoid any potential hazards. It is also important to carefully measure and record all steps in the process to ensure accurate results.

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