Author: Kendra

Midterm Self Assessment and Goal-Setting – Chem 12

Download

Download

Download

Download

Strengths and Weaknesses

After reviewing my strengths and weaknesses in chemistry, I’ve noticed that I am able to understand how reactions speed up or slow down (kinetics), but sometimes struggle with understanding the balance in reversible reactions (equilibrium). In solutions, I’m confident in solving concentration problems, but occasionally miss important factors affecting solubility.

Reflecting on what we’ve learned so far, I find kinetics easy because it’s logical and the math makes sense. Equilibrium is more difficult to understand because of the concepts. In solutions, I like the practical side of solving concentration problems, but I need to pay more attention to the details of solubility.

CRISPR-Cas9 Modelling

One of the technologies that shows the great discoveries in science is CRISPR-Cas9. It is a technique for gene editing, and it can can alter our understanding of our genes, and even change the genes themselves. CRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeats, and it is found in bacteria as their defence mechanism that allows the bacteria to recognize and fend off future attacks. Cas9 is an enzyme that is produced by CRISPR that can cut off certain parts of DNA and turn off specific genes. CRISPR-Cas9 can allow researchers to program Cas9 and make it edit specific genes within an organism’s DNA. This technology opens up many possibilities, from curing genetic diseases to helping studies about drugs/medications, and even editing the genes of embryos before they are born for specific traits. We have been exploring CRISPR-Cas9 through paper models that imitate the process of gene cutting and replacing which allow us to have a physical and visual representation of the process that CRISPR-Cas9 goes through.

The CRISPR-Cas9 system has two key components, the Cas9 protein, and a small RNA molecule known as guide RNA (gRNA). The gRNA is designed to be complementary to a specific target gene sequence, guiding Cas9 to the desired location in the DNA. Researchers then create a custom gRNA to target a specific gene by matching the gene’s sequence they want to edit. Next, The gRNA binds to the complementary DNA sequence within the target gene. Cas9 is guided by the gRNA to the precise location in the DNA where the gene is situated. Once the Cas9-gRNA complex locates the target gene, Cas9 act as scissors which create a double-strand break in the DNA at that specific location. After the DNA is cut by Cas9, the cell’s natural repair mechanisms come into play. There are two primary repair pathways: Non-Homologous End Joining (NHEJ) and Homology-Directed Repair (HDR). NHEJ often leads to small insertions or deletions, disrupting the target gene’s function and effectively “knocking out” the gene. When the goal is to correct a mutation, the HDR pathway is used. A template DNA with the desired correction is introduced alongside the Cas9-gRNA complex. The cell uses this template DNA to repair the break, incorporating the desired correction into the genome. CRISPR-Cas9 can be used in many different ways, such as treating genetic disorders by repairing or replacing mutated genes, studying gene function and regulation, creating genetically modified organisms for research, agriculture, and medicine, enhancing disease resistance in crops, developing new therapies for diseases such as cancer and HIV, and advancing gene therapy for genetic conditions. However, we have to also think about the ethical side of using this technology, especially in humans. This technology is very promising for gene editing but should also be used responsibly.

The paper model of the CRISPR-Cas9 process allowed us to have a more hands-on approach to learning how the genes are altered because we were able to actually cut the paper and add mutations to the RNA, which is what happens with CRISPR-Cas9, and even tape it back together to mimic the process of how CRISPR edits the genes. It also allowed us to see the template DNA and how the DNA is copied into the Cas9-gRNA. However, the paper model did not include the actual end product of using CRISPR, and it was also obviously not as detailed as the real thing, so there are some drawbacks to using models such as this one to conduct our learning. To better improve the model, there could be a digital simulation which allows us to have a visual 3D representation of CRISPR-Cas9 instead of just a flat paper model, but the paper model allowed us to cut the genes ourselves which made it more interactive and interesting for us.

Using models to teach scientific concepts to others is a highly effective method for educating both students and the general public about science. Firstly, models offer a visual representation of often abstract scientific ideas, making it easier for people to understand complex concepts. Their visual appeal also allows for more engagement in the activity compared to reading or listening alone. Additionally, models can simplify difficult concepts, breaking them down into manageable components, allowing learners to establish a solid understanding before adding on complex details. Models also come in various forms, including hands-on models and interactive simulations, which encourages experimentation, leading to a deeper understanding of scientific principles. However, inaccurate or misleading models can create misunderstandings, emphasizing the importance of scientific accuracy in model design. Some concepts may also need the pairing of models with real-world examples. People also have many different learning styles, and while some models are better for others, some people may prefer different learning methods such as kinesthetic approaches or reading.

Works Cited:

“Natural Functions of CRISPR-Cas.” Mpg.De, https://www.mpg.de/11823901/crispr-cas-functions. Accessed 23 Oct. 2023.

“What Are Genome Editing and CRISPR-Cas9?” Medlineplus.Gov, https://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/. Accessed 24 Oct. 2023.

“Questions and Answers about CRISPR.” Broad Institute, 17 Dec. 2014, https://www.broadinstitute.org/what-broad/areas-focus/project-spotlight/questions-and-answers-about-crispr.

EFPH11 – Bento Box

For this Bento Box assignment on Thomas King’s Deep House, I created an interactive image using Genially, and the objects used in the image symbolically represent different elements in the book. By clicking on the interactive buttons, you can access more information about the book.

Download

Base Identification Project

Title: Determining the Base of Oxalic Acid Dihydrate

Purpose

  • The purpose of this lab is to accurately determine the base and the molar concentration, of oxalic acid dihydrate (C2H2O4·2H2O) solution through a titration and flame test. By accurately determining its base, we can understand its chemical behavior and properties and optimize its usage in various processes.
  • In this experiment, we performed a titration using H2O as our base, against a known volume of the oxalic acid dihydrate solution. The reaction between the acid and base will form water and a salt, sodium oxalate (Na2C2O4). The balanced chemical equation for the reaction is as follows:

C2H2O4·2H2O + 2Ca(OH)2 → Ca(C2O4) + 4H2O

List of Materials

  • Oxalic acid dihydrate (C2H2O4·2H2O) 0.4g
  • 100ml H2O
  • Analytical balance
  • Burette
  • Burette clamp
  • Funnel
  • Pipette
  • Beaker
  • Volumetric flask
  • Stirring rod
  • Phenolphthalein indicator
  • Bunsen burner
  • Wire loop
  • Lighter/Striker
  • Safety goggles

attire

  • protective clothing
  • closed-toe shoes
  • hair tie

Procedure

  1. Preparations
  • read over the procedure to understand the lab and its purpose
  • ensure that you are wearing proper lab attire, put goggles on, and sanitize hands
  • gather materials and clean/rinse all of them

2. Weighing of Oxalic Acid Dihydrate

  • weight 0.4g of oxalic acid dihydrate (C2H2O4·2H2O)
  • record the weight of the oxalic acid dihydrate

3. Dissolution of Oxalic Acid Dihydrate

  • transfer the weighed oxalic acid dihydrate to a clean and dry beaker
  • add 100ml of H2O to the beaker
  • stir the mixture using a stirring rod until all the solid has been dissolved which will form a clear solution
  • add a few drops (we used 3)  of phenolphthalein indicator to the solution to help the ending visual results

4. Titration

  • set up a burette, making sure that it is clean and free of any air bubbles
  • fill the burette with the prepared base solution
  • record the initial volume (V1) of the base solution in the burette
  • slowly add the base solution from the burette into the oxalic acid solution int he beaker, while stirring with a stirring constantly
  • continue the addition until a permanent colour change is observed, which indicates its neutralization
  • using the phenolphthalein indicator, the solution should turn from colourless to a pale pink
  • record the final volume (V2) of the base solution in the burette

5. Repeating titration procedure

  • perform titration 2 more times using fresh samples of the oxalic acid dihydrate
  • calculate the average volume of H2O used in the titrations

6. Flame Test

  • Safety precautions: ensure that your work environment is a well-ventilated area and has appropriate safety equipment
  • Clean wire by dipping it in water and holding it in the flame until it burns off any impurities, repeat until clean
  • Light the bunsen burner
  • Soak the wire in the unknown solution
  • hold it above the bunsen burner
  • watch as the flame changes colour and write down any observations and its final colour
  • compare the observed flame colour with a reference flame colour chart or a table that indicates the characteristic colours associated with different metal ions
  • Identify the metal ion present in the compound based on the observed flame color.

Metal Ion Flame Test Colours Chart – Compound Interest

Our flame burned orange, which led us to believe that the base was calcium (Ca).

7. Calculation of concentration

  • calculate the volume of the base solution used in the titration by doing: V=V2-V1
  • calculate the concentration of the base solution using the volume of the base used (V) and the known concentration

Work:

V: V2-V1 = 25.7 – 15.7 = 10.0

concentration of the base solution:

find mol of Ca(OH)2: M(L)

0.03M (0.0157L)

mol of Ca(OH)2 = 0.000471

concentration of base solution: mol/L

0.000471/0.01567 L

M = 0.03

 

Pictures

 

Data Table for Titration Data

MOLARITY OF H2O TRIAL 1 TRIAL 2 TRIAL 3
initial reading of burette 10. 10. 10.
final reading of burette 25.5 25.8 25.7
mL base used 15.5 15.8 15.7
average mL of base 15.7

Conclusion

The objective of the experiment was to determine the concentration of a base solution using a titration method to find the concentration of the acid first, and find the identity of the base as well. We found that the base solution, has a concentration of 0.03 M. We found the identity of the base to be calcium hydroxide Ca(OH)2.

We chose to follow this procedure because the purpose of a titration is to determine the unknown concentration of a substance by comparing it to a known concentration. By measuring the volumes, we can calculate the concentration of the substance being analyzed. So we were able to find the concentration of the solution, but then we had to find the identity of the base, which we did with a flame test. The flame test determined that our base solution was calcium hydroxide.

During the experiment, the volume of the base solution used in three trials was measured, resulting in values of 15.5 mL, 15.8 mL, and 15.7 mL. The average volume of the base used was calculated as 15.7 mL.

Using the known concentration of the base and the volume of the base solution used, the concentration of the base solution was determined to be 0.03 M.

This conclusion suggests that the concentration of the base solution remained consistent throughout the experiment, as the calculated concentration closely matched the known concentration. It also indicates that the titration method used to determine the concentration of the base solution was accurate and reliable.

Errors and how to fix them:

1. Instrumental errors can arise from inaccuracies or limitations in the laboratory equipment used. In this experiment, the burette readings could have given us potential instrumental errors.

How to fix it:
– Ensure the burette is properly cleaned before the experiment and periodically checked for accuracy.
– Use a burette with a clear and accurate scale, making it easier to read and reduce parallax errors.
– Take multiple readings and average them to improve accuracy and makes up for any individual errors.

2. Contamination or impurities in the reagents or equipment can affect the accuracy of the experiment. For example, if the base solution or the burette was contaminated with another substance, it could change the volume measurements or react with the solution, leading to incorrect results.

How to fix it:
– Handle the tools used properly to avoid contamination from outside sources
– Make sure that the equipment is thoroughly cleaned and rinsed to remove any residue from previous use.
– Ensure that the chemicals are pure to minimize the risk of impurities affecting the experiment’s results.

Download