Kylie Sharron Mr. Van Ness Chemistry Honors Period 4 23 November 2015 Engendering Extreme Frustration in Sophomores: Double Replacement Reactions Lab Background Information: A double replacement reaction, also called a double displacement reaction, is a type of chemical reaction in which two compounds react, and the anions and cations of the two reactants switch places to form two new compounds (products). A general equation for a double replacement reaction would be: AX + BY → AY + BX, along with any states of matter subscripted after each compound. Simply put, a double replacement reaction is the exchange of positive ions, or cations, between two compounds to form two new compounds. A precipitation reaction is a double replacement reaction in which two aqueous reactants …show more content…
form a solid and another aqueous product (Zumdahl 167). The solid that’s forms in an insoluble salt, called a precipitate. When two aqueous compounds are combined, a precipitate does not always form. If both compounds are composed of ions that are soluble and no ions that are insoluble, then both products would be aqueous, and this reaction would be just a double replacement rather than a precipitation reaction. Whether or not a precipitation reaction will occur can be predicted using the solubility rules for common ions (Schaffer). One can determine the solubility of the products of a reaction (in the molecular equation) by referring to the solubility rules before writing a net ionic equation. In order to discern whether or not a reaction has taken place between two dissolved compounds, one must look for a precipitate (solid), a color change, a temperature change, or a change in physical state. For example, when combining Magnesium Nitrate [Mg(NO3)2] and Sodium Hydroxide [NaOH], which are both aqueous solutions, one of the products, Mg(OH)2, is a solid (precipitate). This evidence shows a change in physical state, indicating a chemical reaction has occurred. Observations: The initial substances, pictured below, were for the most part, clear fluids. The three substances that differed from the rest were Potassium Ferricyanide, Iron (III) Nitrate, and Copper (II) Nitrate. Other substances that looked slightly opaque were only so due to container that were not completely clear and unclean dishes. Potassium Ferricyanide is a dark yellow liquid that leaves a neon green residue on the walls of its bottle. Iron (III) Nitrate is a rust-orange colored liquid and has the consistency of water, similar to the other chemical used in the lab. Copper (II) Nitrate is a light blue liquid with the same consistency as the other compounds. Many of the substances we used were hazardous and has safety warnings on the bottles. Most chemicals were mild skin irritants, at the least, and many were potentially much more harmful. Potassium Ferricyanide is one of these mild skin irritants, but contact with strong acids would release the toxic gas, HCN. Sodium Carbonate and Magnesium Nitrate are irritating to body tissues, while Zinc Nitrate and Iron (III) Nitrate are corrosive to body tissues. Both Zinc Nitrate and Copper (II) Nitrate are toxic by ingestions. Any direct contact with chemicals can be dangerous and potentially harmful to those who come in contact with them. The colors formed in these reactions varied among lines and columns of the table. Our group organized the chemicals in the testing tray in the same fashion as the data table given in our labs. In this way, each column and row represents its own chemical compound. Below are pictures of the tray on both a white background, to easily see the colored products, and a black background, to easily see the clear products that did not result in a precipitation or a color change. Iron (III) Nitrate and Potassium Ferricyanide formed a brown color, even though the initial compounds were yellow and orange. Other reactions that resulted in a change in color (whether or not a precipitate formed) include: Zinc Nitrate with Potassium Ferricyanide, Copper (II) Nitrate with Potassium Ferricyanide, Iron (III) Nitrate with Sodium Chloride, and Iron (III) Nitrate with Sodium Carbonate. Pre-Lab Questions: A double replacement reaction is a chemical reaction in which two types of anions are exchanged between cations.
Any reaction that begins with reactants both composed of cations and anions, and these anions switch cations in the products, it is a double replacement reaction. In order to decide whether or not a double replacement reaction occurred in the chemical reaction, a precipitate and/or a color change would be indicative. These changes show that the initial compounds have been manipulated in the reaction. One should look for these changes as evidence in order to determine the type of reaction taking place. Many hazards are associated with chemicals in this lab. Most of the chemicals used are irritating when they come in contact with your eyes, skin, or body tissues. Some chemicals are more dangerous, and can be corrosive to your body tissues. In one case, a chemical, when combined with any acids, can produce a toxic gas. In order to protect against these hazards, one must wear safety goggles throughout the entire lab as well as when cleaning up after the lab. Also, one should avoid contact with the chemicals and use extreme caution when handling each of the
chemicals. The chemicals include the following: Potassium Nitrate (KNO3), Zinc Nitrate (Zn(NO¬3)3), Potassium Ferricyanide (K3Fe(CN)6), Sodium Hydroxide (NaOH), Magnesium Nitrate (Mg(NO3)2), Copper (II) Nitrate (Cu(NO3)2), Sodium Phosphate (Na3PO4), Sodium Chloride (NaCl), Iron (III) Nitrate (Fe(NO¬3)3), Calcium Nitrate (Ca(NO3)2), Sodium Sulfate (Na2SO4), and Sodium Carbonate (Na2CO3). Lab Data: Double Replacement Reactions Potassium Ferricyanide Sodium Phosphate Sodium Sulfate Sodium Hydroxide Sodium Chloride Sodium Chloride Potassium Nitrate N.R. N.R. N.R. N.R. N.R. N.R. Magnesium Nitrate N.R. N.R. N.R. Precipitate N.R. Precipitate Iron (III) Nitrate Color Change (yellow to brown) Precipitate N.R. Precipitate Color Change (clear to yellow) Precipitate Zinc Nitrate Precipitate N.R. N.R. Precipitate N.R. Precipitate Copper (II) Nitrate Precipitate N.R. N.R. Precipitate N.R. Precipitate Calcium Nitrate N.R. N.R. N.R. Precipitate N.R. Precipitate *N.R. means ‘No Reaction’ There were 13 reactions that formed precipitates. These precipitation reactions include: Zinc Nitrate with Potassium Ferricyanide [Zn(NO¬3)3+K3Fe(CN)6], Copper (II) Nitrate with Potassium Ferricyanide [Cu(NO3)2 +K3Fe(CN)6], Iron (III) Nitrate with Sodium Phosphate [Fe(NO¬3)3+ Na3PO4], Sodium Hydroxide with Magnesium Nitrate [NaOH +Mg(NO3)2], Sodium Hydroxide with Iron (III) Nitrate [NaOH + Fe(NO¬3)3], Sodium Hydroxide with Zinc Nitrate [NaOH+ Zn(NO¬3)3], Sodium Hydroxide with Copper (II) Nitrate [NaOH+ Cu(NO3)2], Sodium Hydroxide with Calcium Nitrate [NaOH +Ca(NO3)2], Sodium Carbonate with Magnesium Nitrate [Na2CO3 + Mg(NO3)2], Sodium Carbonate with Iron (III) Nitrate [Na2CO3+ Fe(NO¬3)3], Sodium Carbonate with Zinc Nitrate [Na2CO3+ Zn(NO¬3)3], Sodium Carbonate with Copper (II) Nitrate [Na2CO3+ Cu(NO3)2], and Sodium Carbonate with Calcium Nitrate [Na2CO3 + Ca(NO3)2]. The reactions that resulted in color changes were Iron (III) Nitrate with Potassium Ferricyanide [Na2CO3+ K3Fe(CN)6] and Iron (III) Nitrate with Sodium Chloride [Na2CO3+ NaCl]. The 13 balanced precipitation reactions are listed below: • Mg(NO3)2(aq) + 2NaOH(aq) → Mg(OH) 2(s) ¬+ 2NaNO3(aq) • Mg(NO3)2(aq) + Na2CO3(aq) → MgCO3(s) ¬+ 2NaNO3(aq) • Fe(NO3)3 (aq) + Na3PO4(aq) → FePO4(s) + 3NaNO3(aq) • Fe(NO3)3 (aq) + 3NaOH(aq) → Fe(OH)3(s) + 3NaNO3(aq) • 2Fe(NO3)3 (aq) + 3Na2CO3(aq) → Fe2(CO3)3(s) + 6NaNO3(aq) • Zn(NO3)2(aq) + 2NaOH(aq) → Zn(OH)¬2(s) + 2NaNO3(aq) • Zn(NO3)2(aq) + Na2CO3(aq) → ZnCO3(s) + 2NaNO3(aq) • Cu(NO3)2(aq) + 2NaOH(aq) → Cu(OH)2(s) + 2NaNO3(aq) • Cu(NO3)2(aq) + Na2CO3(aq) → CuCO3(s) + 2NaNO3(aq) • Ca(NO3)2(aq) + 2NaOH(aq) → Ca(OH)2(s) + 2NaNO3(aq) • Ca(NO3)2(aq) + Na2CO3(aq) → CaCO3(s) + 2NaNO3(aq) • 3Zn(NO3)2(aq) + 2K3Fe(CN)6(aq) → Zn3(Fe(CN)6)2(s) + 6KNO3(aq) • 3Cu(NO3)2(aq) + 2K3Fe(CN)6(aq) → Cu3(Fe(CN)6)2(s) + 6KNO3(aq) The 2 color-change reactions are listed below: • Fe(NO3)3(aq) + K3Fe(CN)6(aq) → 3KNO3(aq) + Fe(Fe(CN)6)(aq) • Fe(NO3)3(aq) + 3NaCl(aq) → FeCl3(aq) + 3NaNO3(aq) Many of the precipitation reaction also involved a color change. A reaction could not be categorized as both precipitation AND color change, so those that resulted in both were put in the precipitation category. The only reactions in the color-change category changed colors but did not form a precipitate. Conclusion: The goal of the Double Replacement Reactions Lab was to find the combinations of ionic solutions that resulted in the production of a precipitate, or in which a double replacement reaction actually occurs. The lab proved that 13 of the 36 reactions were double replacement reactions that produced precipitates, and 2 of the 36 reactions were double replacement reaction in which a color change occurred. The 21 combinations of compounds that did not result in a reaction were labelled as N.R. In this lab, six chemical compounds were combined with six other compounds, and observations were made before combining as well as after. These observations helped to discern whether or not a double-replacement reaction had occurred. If there was no visible change in the mixture, it was clear that there was no reaction. If it had changed colors, then a double replacement reaction had occurred. And if a solid formed in the mixture, then a certain kind of double replacement reaction occurred, called a precipitation, which is a double replacement that begins with two aqueous solutions and produces one solid product (precipitate) and an aqueous product. When my group conducted this lab, we found a total of 13 precipitation reactions. These reactions were observed correctly, and when checked by writing out the formula for these reactions, resulted in a precipitate. Other reactions that should have resulted in precipitates but weren’t observed as so in the lab include: Zinc Nitrate with Sodium Phosphate, Calcium Nitrate with Sodium Sulfate, and Copper (II) Nitrate with Sodium Phosphate. The ones observed as precipitation reaction were more obviously precipitates than the two unobserved precipitates. Since this lab was performed on such a small scale, it would have been very difficult to be 100% accurate in concluding the precipitates. The ones observed as precipitates were all double replacement reactions that resulted in an aqueous product as well as an insoluble product, which was the precipitate. Through this lab, I learned that accuracy is not guaranteed even if the procedure is followed correctly. Instead of relying on observations to determine whether or not a reaction did or did not occur, write out the chemical equation and determine it that way. By using the solubility rules to determine the solubility of a product, the outcome was more accurate. After doing so, I found three precipitation reactions that I had not previously observed in the lab. In order to take this lab further, I would do it on a larger scale, and determine whether or not the small-scale that this lab was done on originally was the source of the inaccuracy. I could hypothesize that the previous source of inaccuracy in determining precipitation reactions was the small amount of chemicals used, and prove that doing the same experiment using larger amounts would make the resulting precipitates more obvious. References Schaffer, Julie. "Precipitation Reactions." Chemwiki. UCDavis, 01 October 2013. Web. 22 November 2015. Web. Zumdahl, Steven S., and Donald J. DeCoste. Introductory Chemistry: A Foundation. Eight ed. Lexington, MA: D.C. Health, 1993. Print.
There were minimal risks in this section of the practical as glucose is a sugar and is not harmful; however we still wore lab coats and goggles to protect our clothing and eyes from any accidental splashing. We also had to take care when using the pipettes so not to stab ourselves or anyone with them so we had to make sure that we had full concentration on the task and that no one was in too close proximity of you so that they are in danger of getting injured. We also had be careful not to smash any of the glass equipment as this could cause someone to get cut so to prevent this we tried hard not to smash any of the equipment and any breakages are cleared up following laboratory procedures and practices.
The physical characteristic for this reaction is that the colour changes from purple to colourless.
Greta Christina eloquently puts into words something I know in theory, but can be hard to understand in practice in heterosexual relationships. In Are we having sex now or what? Christina details her record keeping of how many people she had sex with, and what she counted as sex. She talks about the limiting misconception of sex only being coitus, and other acts not “counting.” Christina writes of how when she started having sex with women her outdated system of what was sex and what was not sex was completely destroyed. By limiting sex to “penis in vagina,” Christina was discounting some of her favorite sexual experiances, and including ones she did not particularly enjoy.
== = == Hypothesis for the experiment: After I conduct this experiment, I expect and suppose I can recognize and physical changes, identifying the difference these two kinds of changes. Also, I will be able to know some physical and chemical properties of copper (II) sulfate, water, iron, sodium carbonate, hydrochloric acid and magnesium and identify if it is a chemical change or physical change in each part of the experiment.
The purpose of this lab is to stay safe no matter what you're doing in
Stalcup, A. (2013). Surviving toxic work environments. Analytical & Bioanalytical Chemistry, 405(4), 1145-1147. Retrieved from EBSCOhost Database (AN: 84944726)
→ Wear clean lab coats; for additional protection in the hood use a fresh, closed front lab coat with gloves that overlap the cuffs. Protective eyewear should be used when appropriate. Lab coats used for cell culture should not leave the cell culture area.
Nuclear Reactions is a process altering the energy, structure, or composition of atomic nuclei. In a reaction two nuclei or nuclear particles collide to produce a completely different product than the original nuclear particles. Although this is exceptionally rare occurrence a principal reaction includes 2 particles colliding. In most cases the particles will just collide and separate, this process is known as elastic collision, which is not a nuclear reaction. Confused with and similar to the Nuclear Reaction, a Chemical reaction only involves the atoms electrons. In an actual Nuclear Reaction only the atoms nucleus is involved.
Safety standards for all laboratories should be designed to eliminate risks due the use of potentially dangerous materials. All laboratories contain some form of potential hazards, and the actions and attitudes of those working within the laboratory are who sets precedence of their safety and others surrounding them. Their actions can also effect not only the laboratory but the community that surrounds the location. The manual identifies the biological agents that are used within the laboratory, and points out the exposure mechanisms of these biological agents. It includes the methods of evaluation and control of the biological agents, and covers the methods of sampling biological agents.
Some are life threating while others are minors. For instance, one of the most dangerous would be exposure to blood, body fluid, and tissues. It is the most dangerous because if the MLT has a rip in her gloves she touches the specimen she would be contaminating it and she would not get the proper result. Also the specimen may contain infectious agents which can cause very threating to the MLT health.
More than 375,000 nail technicians face possible health hazards everyday (“Health Hazards”). Today’s salons are investing in the latest products. Sanitation is the most important in any salon to prevent disease or injury to cosmetologists and for clients. The ingredients in these hair products are becoming stronger for some clients to handle. Cosmetologists need to understand how to keep ourselves and our clients safe. Tools, implements, and cleaning furniture is the most important. Customers are always going to be coming in and out of the salon. Cosmetologist will not always know who the person is in the salon. Wash and sanitize your hands before and after a client. Wearing personal protective equipment (PPE) will also help prevent disease (Frangie). To prevent disease and bacteria, cosmetologists need to sanitize the tools and furniture before and after they give a service to a client.
...s and hoses, control buttons, switches, hand pieces, and X-ray units (Collins). After every patient’s visit, the operatory is to be sterilized and disinfected. All areas that were that were not covered with a barrier, or if the barrier was compromised, must be wiped down with surface disinfectants similarly used in hospitals. OSHA requires disinfectants to be potent enough to fight against HIV and HBV infections (Collins). If there is any blood present on a surface, tuberculocidal type disinfectant should be utilized.
Safety is definitely not something to be cast aside so quickly as working with plants can be very dangerous. One should make sure to have the proper equipment before working with any kind of plant. For protection a person should have a pair of dragon-hide gloves, earmuffs, and a wand. A quick checklist of everything needed should always be gone over before beginning any type of handling with the plants. Also, while working in the lab you should access to a copious supply of dittany, wear closed toe shoes, an apron, and a mask if necessary. Failing to have the proper safety equipment can cause irrevocable damage and it is shocking how frequent accidents happen just by not having the proper equipment.
In the lab, several rules are in place to ensure a safe and productive experience for those who are working. For example, open-toed shoes, dangling jewelry, food and drinks are prohibited in the lab to prevent both accidental injury of the students as well as potential damage to the lab equipment.
Chemical hazards are either inhaled or absorbed through the skin or both. It may cause illness to some workers who are sensitive to the chemicals such as skin irritation or respiration problems. Chemical hazards mostly happen in laboratory and factory.