Answer:
a. 750Hz, b. 4.0ppm, c. 600Hz
Explanation:
The Downfield Shift (Hz) is given by the formula
Downfield Shift (Hz) = Chemical Shift (ppm) x Spectrometer Frequency (Hz)
Using the above formula we can solve all three parts easily
a. fspec = 300 MHz, Chem. Shift = 2.5ppm, 1MHz = 10⁶ Hz, 1ppm (parts per million) = 10⁻⁶
Downfield Shift (Hz) = 2.5ppm x 300MHz x (1Hz/10⁶MHz) x (10⁻⁶/1ppm)
Downfield Shift = 750 Hz
The signal is at 750Hz Downfield from TMS
b. Downfield Shift = 1200 Hz, Chemical Shift = ?
Chemical Shift = Downfield shift/Spectrometer Frequency
Chemical Shift = (1200Hz/300MHz) x (1ppm/10⁻⁶) = 4.0 ppm
The signal comes at 4.0 ppm
c. Separation of 2ppm, Downfield Shift = ?
Downfield Shift (Hz) = 2(ppm) x 300 (MHz) x (1Hz/10⁶MHz) x (10⁻⁶/1ppm) = 600 Hz
The two peaks are separated by 600Hz
Answer:
Four electrons are present in the valence shell of Silicon.
Explanation:
Valence shell electrons are those electrons which are present in the outermost shell of an atom. These valence shell electrons are responsible for in the formation of bonds with other atoms.
Silicon having atomic number 14 has fourteen electrons in its neutral state and has the electronic configuration as follow;
1s², 2s², 2p⁶, 3s², 3p²
In given configuration the valence shell (outermost shell) is 3 and the number of electrons present in it are four i.e. 3s² and 3p² (2 + 2 = 4) respectively.
Physical properties is actually the measure of properties of a substance without producing any changes init. I.e colour, density melting and boling point. While chemical properties shows that either the specific substance will undergo the r/n or not.
So, gasoline is flammable is it’s chemical property.
The calculated enthalpy of formation of kerosene is 365.4 kJ and heat produced is 78650.3 kJ
For this, we need the normal enthalpy of formation given below
ΔH∘f(CO2)=−393.5kJ/molΔH∘f(H2O)\s=−241.8kJ/molΔH∘f(O2)=0kJ/mol
We shall now determine the enthalpy of kerosene formation:
H rxn = 24 mol H f (CO2) + 26 mol H f (H2O) + 2 mol H f (C12H26) + 37 mol H f (O2) + 1.50 104 kJ = 9444 kJ + 6286.8 kJ + 1500 kJ 2 mol H f (C12H26) = 730.8 kJ H f (C12H26) = 365.4 kJ
Kerosene has a density of 0.74 g/mL.
Kerosene volume (V) equals 0.63 gallons, or 0.63 x 3785.4, or 2384. 8 mL.
We shall now calculate the mass (m) of kerosene:
ρ=mVm\s=ρ×Vm\s=0.749g/mL×2384.mLm\s=1786.2g
We shall now discover the heat that 1786 generated.
Two grams of kerosene
Kerosene's molar mass is 170.33 g/mol.
The mass of two moles of kerosene is equal to 2*170.33*340.66g.
1.50104kJ of heat are generated by 340.66 g of kerosene.
1786 produced heat.
Kerosene 2 grams = 1.50 104 kJ 340.66 1786.2 g = 78650.3 kJ
Learn more about enthalpy here-
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40 drops of blood in a tube that holds 2 mL
