Is BaSO4 soluble or insoluble?

Answer: BaSO4 would typically be considered insoluble due to the presence of a sulfate ion. This usually precludes an ion from disassociating easily in an aqueous solution; this being water. 

The idea of BaSO4 being considered insoluble is further borne out in the Ksp values. While these cannot be directly related to molar solubility, they provide a strong hint that Barium sulfate is more stringent than other comparable molecules. For example Ba(OH)2's ksp is approximately seven orders of magnitude less which means that it is much more likely to ionize. You can tell that the molar solubility of barium hydroxide is orders of magnitude greater without performing the necessary calculations. As a reminder a compound is considered insoluble if less than 1% of the compound ionizes. 

Barium Products Ksp Values
ksp values of some common Barium products (source)

What is the molar solubility of BaSO4?

The calculation is based on the chemical equation for the disassociation of BaSO4 and the formula for ksp (equilibrium constants only include aqueous and gaseous species). 

BaSO4 (s) => Ba(2+)(aq) + SO4(2-)(aq)

ksp = [Ba(2+)][SO4(2-)] 

Since when we ionize we create the two ions in equal molar quantity we can state the following

[Ba(2+)] = [SO4(2-)] = x

$1.1*10^-10 = x^2$

x = $1.05*10^-5$ M

This concentration indicates that less than 1% of the solution is composed of ionized species. 

How does BaSO4 theoretically ionize? 

As the equation (BaSO4 (s) => Ba(2+)(aq) + SO4(2-)(aq)) indicates, barium sulfate would disassociate and produce the barium and sulfate ion. In the real world; however, the low molar solubility indicates that very little barium sulfate actually ionizes. 

Is H2S Polar or Nonpolar?

Answer: H2S is a polar molecule due to the presence of lone pair electrons at the top of the molecule causing a region of partial negative charge due to electron-electron repulsion. 

H2S has a very similar structure as H2O (see the lewis dot structure for H2O and the polar/nonpolar explanation at the linked addresses). However, due to the larger size of the sulfur atom compared to oxygen, the bond angle (i.e. the smaller angle between the two hydrogen atoms) is only 92˚ compared to 107.5˚ for H2O. Sulfur contains many more electrons which ultimately due to electron-electron repulsion require a lot more space. Nevertheless the decreased electronegativity of sulfur when compared to hydrogen (2.58 vs. 2.20, respectively) means that the molecule is much less polar overall when compared to H2O. This means that it has a much lower melting and boiling point at -82˚C and -60˚C, respectively. Like SO2 the presence of sulfur means that this molecule has a pungent odor in gaseous form although it is colorless. 

H2S Ball and Stick Diagram
H2S Ball and Stick Diagram. Created with MolView.

How is H2S utilized in the real world?

Hydrogen sulfide appears in many different ways within the natural world. For starters it is an important constituent of the sulfur cycle. Bacteria oftentimes convert the sulfur from organic elements to inorganic molecules such as H2S. The main use of hydrogen sulfide is as a storage compound which can be converted to pure sulfur during reactions to form all kinds of sulfur-containing compounds. Hydrogen sulfide may have also caused a mass extinction due to its buildup within the atmosphere. Based on this fact it is not difficult to imagine the toxicity of hydrogen sulfide towards life forms such as human beings. It negatively impacts proper nervous system functioning primarily although it will affect other body systems as well. Nevertheless there are certain organisms adapted to live in high-H2S conditions due to those environments existing in deep underwater volcanic sea vents.  

The Lewis Dot Structure for Acetic Acid (CH3COOH)

Lewis Dot Structure for Acetic Acid
Created by MakeTheBrainHappy.

Above is the Lewis Dot Structure for Acetic Acid (CH3COOH). You could alternatively also draw the structure by including two dots for every bond. As you can see every single element has a filled valence shell with the two oxygen's each containing two lone pairs of electrons, the only instance of this phenomena within the Lewis Structure. In a sense this is a modified structure of methane (CH4) with the replacement of one hydrogen with the replacement of a carboxylic group (-COOH). As we will see the properties we observe within the Lewis structure have a significant impact on the properties of acetic acid.

The Greek Philosopher Theophrastus. Source

What is the history of acetic acid?

Due to the importance of different alcohols such as beer and wine in early civilizations, vinegar became one of the earliest chemical substances that was familiar to ancient peoples. Vinegar is formed by natural fermentation processes and contains approximately 5% acetic acid. One of the earliest mentions of acetic acid was by the Greek Philosopher Theophrastus who explained how to form different pigments, including those for white and green colors, with vinegar as an important constituent ingredient. 

Is Acetic Acid (CH3COOH) Polar or Nonpolar?

Acetic Acid (CH3COOH) is a polar molecule due to the presence of the functional group COOH, a carboxylic acid. It is also an acid in solution, releasing a small number of protons into solution which form H3O+. Due to its polar qualities it is found as a liquid at standard temperature and pressure in relation to its rather light molar mass. It has a melting point is between 16˚C to 17˚C while the boiling point is between 118˚C and 119˚C. These are again elevated due to the polarity of acetic acid. 

How is Acetic Acid (CH3COOH) utilized in the real world?

Acetic acid is useful due to its properties as a polar solvent and building block for other molecules, containing both a methyl (CH3) and COOH functional group. Nearly one third of produced acetic acid is utilized in order to produce "Elmer's glue" material. Inks, paints and coatings are also created via a reaction involving acetic acid. It is frequently utilized as a polar solvent in lab research settings and thereby has been involved in certain medical practices. As mentioned above acetic acid is also present in vinegar which has a variety of household uses; however, the acetic acid is diluted in water to a greater degree than in a research lab.  






Downloading FASTQ Files Quickly utilizing IBM’s Aspera Connect on a LINUX or MAC Machine

Please note that this guide is based on this BioStars thread and this GitHub repository


Procedure:


  1. Download the latest version of Aspera Connect from the IBM “featured client software” section (you may need to install a browser extension as well)


  1. Download the file “ena-fast-download.py” from wwood’s GitHub repository


  1. Open the script in your favorite python editor and scroll down to the bottom. Add the specific file path to the ascp field (addition highlighted below)


aspera_commands = []

    for url in ftp_urls:

        quiet_args = ''

        if args.quiet:

            quiet_args = ' -Q'

        cmd = "/Users/USER/Applications/Aspera\ Connect.app/Contents/Resources/ascp{} -T -l 300m -P33001 {} -i {} era-fasp@fasp.sra.ebi.ac.uk:{} {}".format(

            quiet_args,

            args.ascp_args,

            ssh_key_file,

            url.replace('ftp.sra.ebi.ac.uk',''), output_directory)

        logging.info("Running command: {}".format(cmd))

        subprocess.check_call(cmd,shell=True)


logging.info("All done.") 


  1. Save the file. Move the file to the directory where you want FASTQ files to be deposited into. Run the following command in terminal for each accession number (example highlighted):


./ena-fast-download.py ERR1739691 --ssh_key osx 


Note: Sequential commands can be done through a looped text file call or with the ; operator (ex. ./ena-fast-download.py key1 --ssh_key osx ; /ena-fast-download.py key2 --ssh_key osx)


Note 2: For this method it is recommended that you utilize a bash terminal.