Answer:
The number of moles of benzaldehyde = 0.0253 moles
Explanation:
The molecular formula of benzaldehyde is C₇H₆O
Its molecular mass is calculated from the atomic masses of the constituent atoms.
C = 12.0 g: H = 1.0 g; O = 16.0 g
Molecular mass = ( 12 * 7) + (1 * 6) + (16 * 1) = 106.0 g/mol
Number of moles of substance = mass of substance/ molar mass of the substance
mass of benzaldehyde = 2.68; molar mass = 106.0 g/mol
Number of moles of benzaldehyde = 2.68 g/ 106 g/mol = 0.0253 moles
Therefore, the number of moles of benzaldehyde = 0.0253 moles
Explanation:
Combustion produces energy. Where does all this energy come from? Energy is stored in the chemical bonds that hold the carbon and hydrogen atoms together. When the atoms are rearranged, the bonds are broken, releasing energy.
Remember, covalent compounds are compounds with bonds between two non-metals. Ionic bonds are those between a metal and a non-metal.
To determine if an element is a metal or non-metal, simply look at the periodic table! So...
a. Li is found on the left side while F is found on the right. A bond between a metal and a non-metal. This is an ionic bond.
b. Mg is found on the left side while S is found on the right. A bond between a metal and a non-metal. This is an ionic bond.
c. This is a tricky one. ammonia, or NH3, is covalent. You just have to remember this one. It has no net charge, unlike its brother NH4 (which has a 1+ charge put is still covalently bonded). Hydrogen has weird properties!
d. Ca is found of the left side while Cl is found on the right. A bond between a metal and a non-metal. This is an ionic bond. Also consider the charges! Ca has a charge of 2+ but Cl only has a charge of 1-. This is why there are 2 Cloride atoms.
Answer: ≈ 67.4 g
Explanation:
A(t) = amount remaining in t years = A0ekt, where A0 is the initial amount and k is a constant to be determined. Since A(1690) = (1/2)A0 and A0 = 80, we have 40 = 80e1690k 1/2 = e1690k ln(1/2) = 1690k k = -0.0004 So, A(t) = 80e-0.0004t Therefore, A(430) = 80e-0.0004(430) = 80e-0.172 ≈ 67.4 g
Answer:
The molarity of the Pb(NO3)2 solution is 0.24 M
Explanation:
Assuming there was no loss during filtration, we can calculated amount of moles Pb(NO3)2 from the 13.25 g of PbCl2 ussing molar mass of PbCl2
13.25 g / 278.1 g = 0.04 moles of PbCl2
According balanced equation 2NaCl + Pb(NO3)2 = 2NaNO3 + PbCl2, 1 mol of Pb(NO3)2 produces 1 mol of PbCl2. So, 0.04 moles of Pb(NO3)2 produces PbCl2
Molarity is = moles of solute/volumen of solution (L)=0.04/0.2= 0.24
I hope my answer helps you