If I sell 10g of 14k 4 melt value, will I get less 4 the 5.8g of gold in that 10g of 14k than I would if I sold 5.8g of pure gold?

Two ways to get best value for scrap gold.

1) Sell to a smelter-refiner. 

https://www.midwestrefineries.com/

They claim 95% of gold value. You pay shipping.

2) Other online. May have fees and minimums. Get probably 80% in small amounts.

Florida buyer. https://sellyourgold.com/

3) I live in Las Vegas. They offer about 75% at best price

cash on the spot. Several places like 

Sahara Gold and Silver Buyers

1300 E Sahara Ave, Ste A, Las Vegas, NV 89104

(31.1034768 grams/troy ounce) 

4.492 grams + 2.625 grams = 7.117g > 0.2288 oz  x 1542

$352.82 gold value (yellow gold alloys are low value)

You received $222.24 as 63%

Your Maple Leaf has a better price as sold as-is and is not melted down. You usually get 95% or more. It is 3.11g (not 3.393g) $154.24 was value. He gave you 97.6%.

The scrap pieces you received a local in-store buyer price.

$265 probable Las Vegas price

$335.18 minus about $15 insured mailing = $320.18 maximum 

You cannot undo it, but you received typical decent price for a local buyer, and could have packaged with insurance and mailed it to get close to $100 more money if you waited for a check in the mail, about a week or so.

Maple Leaf you did OK. 

The Three Magi brought Jesus gifts of gold, frankincense and myrrh.  Jesus, who had full use of His reason and His speech even as a Baby, told His mother to divide the gold and give half to the Temple and half to the poor.  He told Mary to give the frankincense and myrrh to the Temple, and she obeyed Him on all three counts, obviously, being His perfect disciple and completely without sin.