Answer:
a three-dimensional shape having eight plane faces, especially a regular solid figure with eight equal triangular faces.
Explanation:
Answer:
The ratio of the number of atoms of gold and silver in the ornament is 197 : 1080.
Explanation:
Let the mass of silver ornament be x.
Mass of gold polished on an ornament = 1% of x= 0.1 x
Moles of silver =
Number of atoms = 
Where : 
= Avogadro number
Moles of gold =
Silver atoms =
Gold atoms =
The ratio of the number of atoms of gold and silver in the ornament:
= 197 : 1080
The chemical reaction is expressed as:
3Ba(NO3)2 + 2Na3PO4 = Ba3(PO4)2 + 6NaNO3
To determine the percent yield, we need to determine the theoretical yield of the reaction from the given amounts of the reactants. We do as follows:
0.3 mol 3Ba(NO3)2 ( 2 mol Na3PO4 / 3 mol Ba(NO3)2) = 0.2 mol Na3PO4
Therefore, the limiting reactant would be Ba(NO3)2 since it is consumed completely in the reaction.
Theoretical yield = 0.3 mol 3Ba(NO3)2 ( 1 mol Ba3(PO4)2 / 3 mol Ba(NO3)2) = 0.1 mol Ba3(PO4)2
Percent yield = actual yield / theoretical yield = 0.095 mol Ba3(PO4)2 / 0.1 mol Ba3(PO4)2 x 100 = 95%
<h3>
Answer:</h3>
= 19.712 kJoules
<h3>
Explanation:</h3>
- Heat of vaporization refers to the amount of heat required to change a unit mass of a substance from liquid to gaseous state without change in temperature.
To calculate the amount of heat, we use,
Amount of heat = Mass × Heat of vaporization
Q = m×Lv
Given;
Mass of liquid Zinc = 11.2 g
Lv of liquid Zinc = 1.76 kJ/g
Therefore;
Q = 11.2 g × 1.76 kJ/g
= 19.712 kJ
Thus, the amount of heat needed to boil 11.2 g of zinc is 19.712 kilo-joules.
