Tutor profile: Laura H.
Subject: Organic Chemistry
When bromoethane is treated with Mg(s)/ether and then added to water, what is the resulting product?
Treating bromoethane with Mg(s)/ether forms the Grignard reagent ethylmagnesium bromide, which is highly nucleophilic as well as highly basic. This reagent will deprotonate the water to form the alkane ethane.
Which has a higher boiling point, ethane or ethanol.
In order to move from the liquid phase to the gas phase, the distance between molecules must increase. Thus, boiling point is determined by the strength of the intermolecular forces (IMFs) which are found between molecules. The stronger the forces, the higher the boiling point. Ethane is a non-polar molecule, so the only IMFs present are London dispersion forces (LDFs). Ethanol has LDFs as well but also has an -OH group that participates in hydrogen bonding. Due to the stronger hydrogen bonding present in ethanol, it has a higher boiling point.
Subject: Basic Chemistry
How many moles of gas are in a 1-litre balloon at STP?
The ideal gas law (pV=nRT) will be used to solve this problem. We are given STP (standard temperature and pressure) conditions, which are a temperature of 273.15K and 1 bar (100kPa). Rearranging the ideal gas law to solve for moles: n = (pV)/(RT). In order for units to properly cancel, we will use R = 8.314462618×10−2 L bar K-1 mol-1 Thus, n = (1bar)(1L) / (8.31...×10−2 L bar K-1 mol-1)(273.15K) = 0.044 mol
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