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Gnesinka [82]
4 years ago
7

It is composed of an alloy that is 90% Platinum and 10% Iridium; having a density of 21.186 g/cm3. What is the volume of the Sta

ndard Kilogram?
Chemistry
1 answer:
oksian1 [2.3K]4 years ago
7 0
The alloy has a density of 21.186g/cc. So for a kilogram or 1000 grams/21.186 g/cc= 45.7 cc. So the answer is 45.7 cc of the allow to make up a kilogram which shows that the density of the allow can be used to calculate the volume of a larger mass ie the kilogram. 
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A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4
san4es73 [151]

Answer:

83.20 g of Na3PO4

Explanation:

1 mole of Na3PO4 contains 3 moles of Na+.

Mole of Na ion to be prepared = Molarity x volume

                 = 0.700 x 725/1000

                     = 0.5075 mole

If 1 mole of Na3PO4 contains 3 moles of Na ion, then 0.5075 Na ion will be contained in:

           0.5075/3 x 1 = 0.1692 mole of Na3PO4

mole of Na3PO4 = mass/molar mass = 0.1692

Hence, mass of Na3PO4 = 0.1692 x molar mass

                                     = 0.1692 x 163.94

                                        = 83.20 g.

83.20 g of Na3PO4 will be needed.

3 0
3 years ago
Read 2 more answers
Given that Δ H ∘ f [ Br ( g ) ] = 111.9 kJ ⋅ mol − 1 Δ H ∘ f [ C ( g ) ] = 716.7 kJ ⋅ mol − 1 Δ H ∘ f [ CBr 4 ( g ) ] = 29.4 kJ
JulsSmile [24]

Answer:

283.725 kJ ⋅ mol − 1

Explanation:

C(s) + 2Br2(g) ⇒ CBr4(g) , Δ H ∘ = 29.4 kJ ⋅ mol − 1

\frac{1}{2}Br2(g) ⇒ Br(g) ,  Δ H ∘ = 111.9 kJ ⋅ mol − 1

C(s) ⇒ C(g) ,  Δ H ∘ = 716.7 kJ ⋅ mol − 1

4*eqn(2) + eqn(3) ⇒ 2Br2(g) + C(s) ⇒ 4 Br(g) + C(g) , Δ H ∘ = 1164.3 kJ ⋅ mol − 1

eqn(1) - eqn(4) ⇒ 4 Br(g) + C(g) ⇒ CBr4(g) , Δ H ∘ = -1134.9 kJ ⋅ mol − 1

so,

   average bond enthalpy is \frac{1134.9}{4} = 283.725 kJ ⋅ mol − 1

4 0
3 years ago
Which of the following are examples of chemical changes? Select all that apply.
Natali5045456 [20]

Answer:

b. milk spoiling and c. firecrackers exploding

Explanation:

These are both chemical changes, the composition of them change when this happens and it cannot be reversed

6 0
2 years ago
When trying to determine whether or not an atom gives up electrons easily, do chemists look at electronegativity or ionization p
Archy [21]
Here I found some info at Yahoo answers: https://answers.yahoo.com/question/index?qid=20090119191941AAB7oAb
The more electronegative an atom is the more unwilling it is to lose its electrons in a compound. If you do try to take a very EN atom away from a compound you'll need to apply a lot of energy for that to happen. I can give an example of a single atom though 

<span>Cl has 7 valence electron filled and every atom wants to be like nobles (noble gases), so it's not going to give an electron away b/c it's really close to being like a noble gas. Noble gases are the most stable atoms, which is why I say stability counts.</span>
4 0
3 years ago
Calculate the volume of hydrogen if you have 12.1 moles of Hydrogen.
vodomira [7]

To Find :

The volume of 12.1 moles hydrogen at STP.

Solution :

We know at STP, 1 mole of gas any gas occupy a volume of 22.4 L.

Let, volume of 12.1 moles of hydrogen is x.

So, x = 22.4 × 12.1 L

x = 271.04 L

Therefore, the volume of hydrogen gas at STP is 271.04 L.

8 0
2 years ago
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