<span>To find the volume of the plate without accounting for the hole firstly
V = (15.0 cm)(12.5 cm)(0.250 cm) = 46.875 cm^3
and the volume of the hole is
(pi)(1.25 cm)^2(0.250 cm) = 1.2272 cm^3
we will subtract the volume of the hole from the rest 45.648 cm^3
the multiply this by the density of the alloy to find the mass
(8.80 g/cm^3)(45.648 cm^3) = 401.701 g.
0.044% of this is Si, so (0.00044)(401.701 g) = 0.17675 g is silicon.
by the number of atoms and using average atomic mass of silicon and Avogadro's number to find the number of silicon atoms:
(0.17675 g)(1 mol/28.0855 g)(6.022E23 atoms/1 mol) =3.794E21atoms of Si
3.10% of these are Si-30:(0.0310)(3.794E18 atoms)=1.176E20 atoms of Si-30 and with two significant figures, 1.2E20 atoms.
hope this helps
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Atomic mass of magnesium = (23.99 x 78.99%) + (24.99 x 10.00%) + (25.98 x 11.01%)
= 24.31 g/mol
Yes. As long as the ratio of solute and solvent is same for both solution, the solution has the same concentration. for example, solution A has 2 ml of water, and 1 ml of sucrose. Solution B has 4ml of water and 2ml of sucrose. Both has a ratio of water to sucrose by 2 : 1. they have the same concentration of 50% sucrose.
The enthalpy change of the reaction when sodium hydroxide and sulfuric acid react can be calculated using the mass of solution, temperature change, and specific heat of water.
The balanced chemical equation for the reaction can be represented as,
Given volume of the solution = 101.2 mL + 50.6 mL = 151.8 mL
Heat of the reaction, q = 
Δ
m is mass of the solution = 151.8 mL * 
C is the specific heat of solution = 4.18 
ΔT is the temperature change = 
q = 
Moles of NaOH = 
NaOH
Moles of 
= 
Enthalpy of the reaction = 
