Diagram A shows the Lewis structure (LS) of CH_2O. The formal charge on each atom is zero.
To get the formal charge (FC) on the atoms, cut each bond in half, as in <em>Diagram B</em>. Each atom gets the electrons on its side of the cut.
Formal charge = valence electrons in isolated atom - electrons on bonded atom
FC = VE - BE
<em>On O:
</em>
VE = 6
BE = 2 lone pairs 2 + 2 bonding electrons = 4 + 2 = 6
FC = 6 – 6 = 0.
<em>On H:
</em>
VE = 1
BE = 1 bonding electron
FC = 1 – 1 = 0
<em>On C:
</em>
VE = 4
BE = 1 in each single bond + 2 in the double bond = 2 + 2 = 4
FC = 4 - 4 = 0
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Answer:
hydrogen oxygen or nitrogen
1070 hours.
1 mole of iron-59 would mass 59 grams, so 0.133 picograms would be 0.133x10^-12 / 59 = 2.25x10^-15 moles of iron-59. Multiplying by Avogadro's number, we can determine the number of atoms of iron-59 we have, so: 2.25x10^-15 * 6.02214x10^23 = 1.35x10^9
Since we have 242 decays over a period of 1 second, we can divide the
number of atoms left by the original number of atoms
(1350000000 - 242)/1350000000
= 1349999758/1350000000
= 0.999999820740741
And calculate the logarithm to base 2 of that quotient.
ln(0.999999820740741)/ln(2)
= -1.79259275281191x10^-7/0.693147180559945
= -2.58616467481524x10^-7
The reciprocal of this number will be the half life in seconds. So
-1/2.58616467481524x10^-7
= -3866729.79388461
And dividing by 3600 (number of seconds in an hour) will give the half-life in
hours.
-3866729.79388461 / 3600 = -1074.091609
So the half life in hours to 3 significant figures is 1070 hours.
Dividing that figure by 24 gives a half life of 44.58 days which is in pretty close agreement to the official half-life of 44.495 days for iron-59.
Answer:
the melting point is the factor what what degrees fahrenheit a metal or other solid substance melts. the significance of knowing the melting point can help you determine how long or how hot to burn the tested object while at the same time determining the safety requirements.
Explanation:
