D. Matter and energy are the same.
Polar covalent bonds so basically the electrons are shared differently.
Answer:
Molarity = moles / volume
moles of HCl = molarity ×volume
= 0.0150 M × 0.08189L
= 0.0123mol
∴ the amount of CaCO3 neutralized by 0.0123 mole of HCl will be in 1:2 ratio.
moles of CaCO3 = 0.0123 mol of HCl× 1mol CaCO3/ 2mol HCl
= 0 .00614 mol
∴ the tablet has 0.00614 mol of CaCO3.
Explanation:
Step 1:
In the above-experiment problem, HCl acid solution is basically treated with CaCO3 base active in the tablet.
The mass of CaCO3 present in the tablet must be obtained in milligram (mg).
First, write down the balanced reaction between HCl and CaCO3
2Hcl aq + CaC03 s ⇒ CaCl2 aq + H2O l + C02 g
CaCO3 and HCl react in 1:2 ratio of moles respectively.
∴ for each mole of calcium carbonate there would be twice the moles of HCl required for neutralization.
Step 2
the volume is 81.89 mL (i.e 0.08189 L) of 0.150 M HCl neutralizes the whole tablet containing unknown amount of CaCO3.
So, the number of moles of HCl present in the taken volume is calculated
Answer:
a)
⇒
⇒
b)
⇒
⇒
Explanation:
A)
Remember that positive number superscripts mean electrons lack and negative numbers mean electrons 'excess' (if we compare it with the neutral element). So, for the case of Fe2+ which is converted to Fe3+, we know that in Fe2+ there is a two electrons lack, while in Fe3+ there is a 3 electrons lack; it means that Fe2+ was converted to Fe3+ but releasing one electron:
⇒
The same analysis is applied to Br2; Br2 is a molecule which is said to have a zero superscript because it is an apolar covalent bond; and it is converted to Br-, which, according to what I wrote above, means that there is a one electron excess. So, Br2 must have received an electron in order to change to Br-; but Br2 can't change to Br- as simple as that because Br2 is a molecule, not an atom; it is a molecule that has two Br atoms, so, Br2 must give two Br- ions as products, but receiving one electron for each one:
⇒
b)
Applying the same, in Mg2+ there is a 2 electrons lack, and in Mg is not electron lack (its superscript is zero), so Mg must have released two electrons in order to change to Mg2+:
⇒
Cr3+ has a 3 electrons lack, and Cr2+ a two electrons one, so, Cr3+ must receive an electron to convert to Cr2+:
⇒