STAAR -ingo Vocabulary Flashcard

STAAR -ingo Vocabulary

Chemistry Review of pOH Calculations

Chemistry Review of pOH Calculations Sometimes you are asked to calculate pOH rather than pH. Heres a review of the pOH definition and an example calculation. Acids, Bases, pH and pOH There are several ways to define acids and bases, but pH and pOH refer to hydrogen ion concentration and hydroxide ion concentration, respectively. The p in pH and pOH stands for negative logarithm of and is used to make it easier to work with extremely large or small values.  pH and pOH are only meaningful when applied to aqueous (water-based) solutions. When water dissociates it yields a hydrogen ion and a hydroxide. H2O ⇆ H OH- When calculating pOH, remember that [] refers to molarity, M. Kw [H][OH-] 1x10-14 at 25 °Cfor pure water [H] [OH-] 1x10-7Acidic Solution: [H] 1x10-7Basic Solution: [H] 1x10-7 How to Find pOH Using Calculations There are a few different formulas you can use to calculate pOH, the hydroxide ion concentration, or the pH (if you know pOH): pOH -log10[OH-][OH-] 10-pOHpOH pH 14 for any aqueous solution pOH Example Problems Find the [OH-] given the pH or pOH. You are given that the pH 4.5. pOH pH 14pOH 4.5 14pOH 14 - 4.5pOH 9.5 [OH-] 10-pOH[OH-] 10-9.5[OH-] 3.2 x 10-10 M Find the hydroxide ion concentration of a solution with a pOH of 5.90. pOH -log[OH-]5.90 -log[OH-]Because youre working with log, you can rewrite the equation to solve for the hydroxide ion concentration: [OH-] 10-5.90To solve this, use a scientific calculator and enter 5.90 and use the /- button to make it negative and then press the 10x key. On some calculators, you can simply take the inverse log of -5.90. [OH-] 1.25 x 10-6 M Find the pOH of a chemical solution if the hydroxide ion concentration is 4.22 x 10-5 M. pOH -log[OH-]pOH -log[4.22 x 10-5] To find this on a scientific calculator, enter 4.22 x 5 (make it negative using the /- key), press the 10x key, and press equal to get the number in scientific notation. Now press log. Remember your answer is the negative value (-) of this number.pOH - (-4.37)pOH 4.37 Understand Why pH + pOH = 14 Water, whether its on its own or part of an aqueous solution, undergoes self-ionization which can be represented by the equation: 2 H2O ⇆ H3O OH- Equilibrium forms between the unionized water and the hydronium (H3O) and hydroxide (OH-) ions. The expression for the equilibrium constant Kw is: Kw [H3O][OH-] Strictly speaking, this relationship is only valid for aqueous solutions at 25 °C because that is when the value of Kw is 1 x 10-14. If you take the log of both side of the equation: log  (1 x 10-14)  Ã‚  log  [H3O]  Ã‚  log  [OH-] (Remember, when numbers are multiplied, their logs are added.) log  (1 x 10-14)  Ã‚  -  14-  14  Ã‚  log[H3O]  Ã‚  log  [OH-] Multiplying both sides of the equation by -1: 14  Ã‚  -  log  [H3O]  -  log  [OH-] pH is defined as  -  log  [H3O] and pOH is defined as -log  [OH-], so the relation becomes: 14 pH - (-pOH)14 pH pOH

Crosstalk IT Coursework Example | Topics and Well Written Essays - 2000 words

Crosstalk IT - Coursework Example The first type of coupling or conductive coupling is a result of the establishment of physical contact between conductors. Inductive crosstalk results when the current passing through a single conductor results in the generation of a similar current in another conductor. The third type of crosstalk or capacitive coupling is the resultant of the coming together of two or more conductors such that they begin to act as a capacitor. Figure 1: Introduction to Crosstalk. Source: polarinstruments.com Crosstalk may be PREVENTED by enabling the positioning of conductors to be at respective distances. Instead, the introduction of insulation between the conductors may also result in the lessening of crosstalk. Practically it is not possible to separate out wires in distances therefore the option for insulation is better. Crosstalk due to inductive capacitance may be eliminated by twisted the inducing cables around each other. The inter-wound cables are often referred to as twisted pair cables. The way crosstalk gets reduced is due to the reduction of the field size cross section on which crosstalk may occur. Thus electromagnetic interference gets reduced considerably. Digital signals are often affected less or not at all by crosstalk. The signals mostly affected are those that are analogue in nature. The term has been chosen owing to my personal experience of handling issues related to it in my organization. The networking setup had old fixtures within the entire organizational setup and had to be replaced with better cables that proposed reduced interferences and thus lesser possibilities of crosstalk. CAT 6 CABLE Ethernet or LAN to put simply is the means by which the computer systems present within a closed area are connected together into a network via hardware cables. The cables used for the said process are of various standards. CAT 6 Cable is one of them. The technology of the Ethernet is integral for organizational networks and so is the presence of CAT 6 cable in it. Figure 2 Cat 6 Cable. Source: http://www.openxtra.co.uk/articles/category-6-cat6-cable It is given the name CAT 6 because it belongs to the sixth generation of cables that have been made for the Ethernet technology. Specifically it may be said that it supports the following gigabit Ethernet technologies: 10BASE-T/100BASE-TX and 1000BASE-T/1000BASE-TX. The cable consists of eight wires just like its predecessor Cat 5 cable. However it is different from its former version in the manner that it makes use of all its 4 pairs in data transfer. The Category 6 Cable was used in the establishment of the Local Area Network of the Organization for which I work. The selection and successful installation of this cable was my task and that is how I encountered it. This cable was preferred over the rest of the available option because it is the latest version of cables that complies fully with the standard Ethernet Protocols fo Data Transfer and provides efficient data transfer without any da ta loss. MP3 MP3 is a short form of MPEG-2 Audio Layer III. It is a standard format for digital music storage that was designed by Motion Pictures Experts Group (MPEG) around mid-1990s. High quality audio files can be created using this standard with extremely optimized storage space. MP3 format is widely used over the internet to share and transfer audio files. How the magic of MP3 works. The