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How many moles of gas must be forced into a 3.5 L ball to give it a gauge pressure of 10.2 psi at 24oC?
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∙ 10y ago
0,1 mole gas
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∙ 7y ago
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Why is the pH of pure water 7?
It almost never is. BUT (pH stands for potential hydrogen) pH is a (negative of) the log of the number of positive ions in the water. At 25 degrees C, thermal agitation in pure water will produce 10 to the minus 7 (moles of) ions per liter, thus pH 7 (at 37 degrees it's 7.4)
How long is the uss enterprise?
The environmental controls aboard the Enterprise are programmed to keep habitat areas of the ship between 23oC/73.4oF to 24oC/75.2oF. Crew and passengers have the option to customise they're quarters to they're personal temperature preference, by telling the computer to adjust.
What is the pH of pure water at temperatures other than 25 degrees Celsius?
I'd have thought a table like this would be in the CRC Handbook of Chemistry and Physics, but I couldn't find it in mine (60th Edition). I did find a table listing the ionization constant for water at several different temperatures, so based on that: * 7.47 at 0oC * 7.27 at 10oC * 7.08 at 20oC * 6.92 at 30oC * 6.77 at 40oC * 6.63 at 50oC * 6.51 at 60oC Note: this does not mean that pure water at 10 oC is alkaline and water at 60oC is acidic! It's neutral in all cases. PS: Per the Handbook, it's actually 24oC where the pH of water is 7.00. At 25oC, it's very slightly less. PPS: It's probably listed in exhaustive detail in the International Critical Tables, but I don't have a set handy.
What are the pH of pure water?
It is usually said to be 7.0. Strictly speaking, this is only true for a particular temperature (24oC). The pH at other temperatures is different, though it's important to understand that the water does not actually become acidic or alkaline as the temperature changes ... it's still neutral, but the pH of a neutral solution is different at different temperatures. Pure water is 7.0 But to the person above me when you heat water and leave it for cooling you need to minus two because all of the floating things e.g feces and icky things like that dissolve and the water is cleansed, but pure is straight form the springs, there is a different answer for everything not all things are the same.
What are the benefits of tourism in menorca?
TOURISM IN AN MEDC OR EU COUNTRY - MENORA CASE STUDYWhere is Menorca?· Menorca is the second largest of the Spanish Balearic Islands in the Mediterranean Sea. It has a population of 67,000 and it has a total land area of 702km2.Why visit Menorca?· Mediterranean Climate - average temp 16oC with an average of 24oC in the summer months, little rainfall in summer (most in the Autumn)· Beautiful and varied landscape· North of Menorca has an uneven and rugged coastline and in the South there are white sandy beaches· Wide range of watersports available (windsurfing; water skiing; scuba-diving etc.)· Other outdoor activities include - horse riding; cycling and potholing.Advantages of Tourism in MenorcaSocio-Economic· Job Creation - tourism is the largest employer in Menorca (Menorca has the lowest unemployment of the Balearic Islands)· Tourism has had a multiplier effect and support many different sectors of the economy e.g. jobs in farming (providing food for hotels); job in the craft industry (providing souvenirs for tourists); ice-cream is a major business.Environmental· Tourism in Menorca has raised awareness of the need to preserve the environmentDisadvantages of Tourism in Menorca·· Shortage of all year employment (tourism is seasonal - in winter months the number of tourists decrease)·· There have been changes in the local way of life due to the demands of tourists and also the increase in foreigners living in Menorca which has become a popular retirement destination·· Some of the early hotels bought in the area were not sensitively designed to fit in with the environment and are seen as eyesores·· There has been some "erosion" of local culture, as it has changed to meet the demands of tourism - in particular a threat to the local language and local traditions.·· With an increasing number of villas and property being bought as second homes / rent-outs for tourists there has been some resentment by locals.Working towards sustainable tourism in Menorca·· Restrictions on development - undeveloped areas remain undeveloped and planning permission has been tightened - there is a height restriction of 2 storeys on hotels within 250km of the coast;·· The government has sought to preserve the traditional language by ensuring all signs are in the local language and by restricting the use of other languages in the advertising of tourist facilities.·· The island has been declared a Biosphere Reserve by the UN - it landscape has significant scenic value and it has been recognised that the diversity of landscape is under threat and that some plant and animal species that can only be found in Menorca are in danger of extinction.
How do you look after goldfish?
This is for beginnersequipment you need:AquariumOf-course you'll need one No one is stupid enough to not have a aquarium, it can be made of glass or acrylic.It comes in many shapes and sizes, Marina Aquariums are the best for beginners because I have one too.:)A sturdy baseThis one is important because without a sturdy base your aquarium is likely to fall. Even if its just a small aquarium because a filled up Marina Aquarium is like OVER 90 CAN OF BAKED BEANS! One more for this subject is that never place the aquarium near a door, window (because sunlight is so strong that it can raise the temperature up and tropical fish might like it but we're talkin about goldfish and its coldblooded), TVs (fish don't really like sudden sound or the raise of temperature) and other articles of furniture. Fish don't really like big things because imagine yourself as a tiny goldfish, and suddenly you got picked up buy a net and SPLASH! your in a totally different place. Then a big massive hand grabs the bag and you are being carried away from your home. few hours later you got put in some glass box and you cant get out. Big massive fingers poking the wall and all you can hear is bang bang bang and some weird people talking and for the rest of your life all you can hear is fingers poking, water splashing and people talking.FilterThe only way to get goldfish poo out off your tank is not by getting a net and start scoping. The only way is to get a slim filter, if you buy the Marina Aquarium they will provide you one. Goldfish do poo a lot, you feed them they poo, you feed again they poo. so if you want to have a clean aquarium then the best thing to do is to buy a slim filter.Heater & thermometerAll fish is coldblooded which mean their body is cold too. you don't really put a real heater inside, instead you have the heat of a light bulb. Oh yes and a thermometer the ones you peal of and then stick on to the surface of the aquarium. It will tell you the exact temperature of the aquarium, you know what I'm going to stop saying aquarium and use tank instead. Gold fish doesn't like temperature over 24oC and also they wont eat at 16oC.LightingThere isn't much to talk about lighting really, the tank must be lit for 8 hours to12 hours. It depends of whether you have real plants in the tank.Gravel and decorationsOnly buy rocks, ornaments and gravel that have be designed for use in a tank. To remind you that you can only put gravel and decorations in the tank when it's not filled with water, after putting the gravel and decorations slowly put a small amount of water then slowly fill the tank.Test kits and water treatmentensure your water is perfect by using water treatment, you can buy them in pet shops or shops that only sell fish as pets. NUTRAFIN AQUA+plus makes tap water safer for fish and coats and protects fish under stress you should have it when you buy the maria tank, NUTRAFIN cycle helps to clear bad bacteria in your tank and helps to reduce the break down of your filter , NUTRAFIN waste control filters the tank surface and cleans gravel , NUTRAFIN clear fast clears cloudy water caused by bacteria.Start with just 1 or 2 fish(1) swich off the tank light, lift the lid and float the bag of fish for 20 minutes to let the fish get use to the temperature.(2)open the bag at the top and add a bit of the tank water.(3)wait 10 minutes and do it again.(4)carefully remove the fish from the bag using a net( do not tip the bag over and dont add any off the water that is in the bag also use a Marina Fish Net if you can get one because it is softer than the normal ones and won't harm the fish.) Finaly leave the fish for 24 hours do not... I repet do not disturb the fish and dont feed it I promise it wont die......ok just put 1 peice of goldfish food or a tiny tiny bit. Then you should change the water once a day for 2 weeks and if it goes well for the first few weeks then you can get more fish but ask the staff at the store to recommend some hardy first fish.AND THATS THE END OF THE LESSON FOR BEGINNERS YOU!first, very crucial step: put it in water, like a fish bowl or tank.2nd step feed it fish food3rd step clean the fish bowl or tank when it gets dirty4th step don't kill it
What are the five factors that affect a sanitizers effectiveness?
CLEANING AND SANITIZING Cleaning and sanitizing procedures must be part of the standard operating procedures that make up your food safety program. Improperly cleaned and sanitized surfaces allow harmful microorganisms to be transferred from one food to other foods. Cleaning Cleaning is the process of removing food and other types of soil from a surface, such as a dish, glass, or cutting board. Cleaning is done with a cleaning agent that removes food, soil, or other substances. The right cleaning agent must be selected because not all cleaning agents can be used on food-contact surfaces. (A food-contact surface is the surface of equipment or utensil that food normally comes into contact.) For example, glass cleaners, some metal cleaners, and most bathroom cleaners cannot be used because they might leave an unsafe residue on the foodcontact surface. The label should indicate if the product can be used on a food-contact surface. The right cleaning agent must also be selected to make cleaning easy. Cleaning agents are divided into four categories: • Detergents - Use detergents to routinely wash tableware, surfaces, and equipment. Detergents can penetrate soil quickly and soften it. Examples include dishwashing detergent and automatic dishwasher detergents. • Solvent cleaners - Use periodically on surfaces where grease has burned on. Solvent cleaners are often called degreasers. • Acid cleaners -- Use periodically on mineral deposits and other soils that detergents cannot remove. These cleaners are often used to remove scale in warewashing machines and steam tables. • Abrasive cleaners -- Use these cleaners to remove heavy accumulations of soil that are difficult to remove with detergents. Some abrasive cleaners also disinfect. Clean food-contact surfaces that are used to prepare potentially hazardous foods as needed throughout the day but no less than every four hours. If they are not properly cleaned, food that comes into contact with these surfaces could become contaminated. Sanitizing Sanitizing is done using heat, radiation, or chemicals. Heat and chemicals are commonly used as a method for sanitizing in a restaurant; radiation rarely is. The item to be sanitized must first be washed properly before it can be properly sanitized. Some chemical sanitizers, such as chlorine and iodine, react with food and soil and so will be less effective on a surface that has not been properly cleaned. Cleaning and Sanitizing 2 Sanitizing Methods • Heat. There are three methods of using heat to sanitize surfaces - steam, hot water, and hot air. Hot water is the most common method used in restaurants. If hot water is used in the third compartment of a three-compartment sink, it must be at least 171oF (77oC). If a high-temperature warewashing machine is used to sanitize cleaned dishes, the final sanitizing rinse must be at least 180oF (82oC). For stationary rack, single temperature machines, it must be at least 165oF (74oC). Cleaned items must be exposed to these temperatures for at least 30 seconds. • Chemicals. Chemicals that are approved sanitizers are chlorine, iodine, and quaternary ammonium. Chemical Sanitizers Different factors influence the effectiveness of chemical sanitizers. The three factors that must be considered are: • Concentration -- The presence of too little sanitizer will result in an inadequate reduction of harmful microorganisms. Too much can be toxic. • Temperature -- Generally chemical sanitizers work best in water that is between 55oF (13oC) and 120oF (49oC). • Contact time -- In order for the sanitizer to kill harmful microorganisms, the cleaned item must be in contact with the sanitizer (either heat or approved chemical) for the recommended length of time. Sanitizer Testing Every restaurant must have the appropriate testing kit to measure chemical sanitizer concentrations. To accurately test the strength of a sanitizing solution, one must first determine which chemical is being used -- chlorine, iodine, or quaternary ammonium. Test kits are not interchangeable so check with your chemical supplier to be certain that you are using the correct kit. The appropriate test kit must then be used throughout the day to measure chemical sanitizer concentrations. Cleaning and Sanitizing 3 Advantages and Disadvantages of Different Chemical Sanitizers Chemical Concentration Contact Time Advantage Disadvantage Chlorine 50 ppm in water between 75 and 100oF 7 seconds Effective on a wide variety of bacteria; highly effective; not affected by hard water; generally inexpensive Corrosive, irritating to the skin, effectiveness decreases with increasing pH of solution; deteriorates during storage and when exposed to light; dissipates rapidly; loses activity in the presence of organic matter Iodine 12.5-25 ppm in water that is at least 75oF 30 seconds Forms brown color that indicates strength; not affected by hard water; less irritating to the skin than is chlorine; and activity not lost rapidly in the presence of organic matter. Effectiveness decreases greatly with an increase in pH (most active at pH 3.0; very low acting at pH 7.0); should not be used in water that is at 120oF or hotter; and might discolor equipment and surfaces. Quaternary Ammonium Compouds U to 200 ppm in water that is at least 75oF 30 seconds Nontoxic, odorless, colorless, noncorrosive, nonirritating; stable to heat and relatively stable in the presence of organic matter; active over a wide pH range Slow destruction of some microorganisms; not compatible with some detergents and hard water Cleaning and Sanitizing 4 Machine Warewashing Most tableware, utensils, and other equipment can be cleaned and sanitized in a warewashing machine. Warewashing machines sanitize by using either hot water or a chemical sanitizing solution. • Check the machine for cleanliness at least once a day. • Make sure all detergent and sanitizer dispensers are properly filled. • Scrape, rinse, or soak items before loading them into the machine. • Load racks correctly and use racks designed for the items being washed. • Check temperatures and pressure at least once a day. • Check each rack as it comes out of the machine for soiled items. • Air-dry all items. • Keep your warewashing machine in good repair. High-Temperature Machines • The temperature of the final sanitizing rinse must be at least 180oF (82oC). For stationary rack, single temperature machines, it must be at least 165oF (74oC). • The machine must have a thermometer installed to measure the temperature of water at the manifold, where it sprays into the tank. Chemical-Sanitizing Machines • Chemical sanitizing machines often wash at much lower temperatures, but not lower than 120oF (49oC). • Rinse water temperature in these machines should be between 75oF and 120oF (24oC and 49oC) for the sanitizer to be effective. Cleaning and Sanitizing in a Three-Compartment Sink 1. Rinse, scrape, or soak all items before washing them in a three-compartment sink. 2. Wash items in the first sink in a detergent solution that is at least 110oF (43oC). 3. Immerse or spray rinse items in the second sink using water that is at least 110oF (43oC). 4. Immerse items in the third sink in hot water or a properly prepared chemical sanitizing solution. 5. Air-dry all cleaned and sanitized items before storing them. Cleaning In Place Equipment 1. Turn off and unplug equipment before cleaning. 2. Remove food and soil from under and around equipment. 3. Remove detachable parts and manually wash, rinse, and sanitize them or run through a warewashing machine. 4. Wash and rinse all other food-contact surfaces that you cannot remove, then wipe or spray them with a properly prepared chemical sanitizing solution. 5. Keep cloths used for food-contact and non-food-contact surfaces in separate properly marked containers of sanitizing solution. 6. Air-dry all parts, then reassemble. 7. Resanitize food-contact surfaces handled during reassembly. Cleaning and Sanitizing 5 Storing Utensils, Tableware, and Equipment Improperly storing cleaned and sanitized equipment, utensils, and linens could allow them to become contaminated before they are used again. Contamination can be caused by moisture from flooding, drips, or splash. Food debris, toxic materials, litter, dust, and other substances might also cause it. Using Chemicals Separate chemicals from food, equipment, utensils, linens, and single-use items. If chemicals are stored directly above or next to any of these items, they could spill onto the item and contaminate it. Only buy chemicals approved for use in a restaurant or food establishment. Store chemicals in their original container away from food storage and food preparation areas. If a chemical is transferred to a new container, label the container with the chemical name, manufacturer's name and address, and potential hazards of the chemical. Material Safety Data Sheets (MSDS) are one way that chemical manufacturers provide hazard information to users, such as foodservice workers. Information on a typical MSDS includes: 1. Contact information -- manufacturer name, address, emergency telephone number, telephone number for information, and the date the MSDS was prepared 2. Hazard ingredients and identity information -- hazardous components in the product 3. Physical and chemical characteristics -- boiling point, vapor pressure, vapor density, solubility in water, specific gravity, melting point, evaporation rate, and appearance and odor 4. Fire and explosion hazard data -- flash point, how to extinguish, special fire fighting procedures, unusual fire and explosion hazards 5. Reactivity data -- stability, incompatibility with other products and substances, hazardous decomposition or byproducts 6. Health hazard data -- signs and symptoms of exposure, medical conditions generally aggravated by exposure, emergency and first aid procedures, health hazards (acute or chronic) 7. Precautions for safe handling and use -- precautions for safe handling and use, such as steps to be taken in case the chemical is spilled; how to dispose; precautions to be taken in handling and storing; and any other precautions, such as respiratory protection, ventilation, protective gloves, eye protection, other protective clothing or equipment. 8. Control measures The Occupational Safety and Health Agency (OSHA) of the US Department of Labor requires that restaurants have a hazard communication program. Material Safety Data Sheets (MSDS) are the foundation of the program. The MSDS must be available for all hazardous chemicals used in your restaurant and so keep them in a binder or in a central file in the establishment. The following information should also be available: • a list of the hazardous chemicals located in each work area; • a description of how employees will be informed about the hazards in using chemicals; and • emergency procedures for spills, leaks or other accidents. Cleaning and Sanitizing 6 OSHA also requires that all containers of hazardous chemicals: • be properly labeled, tagged, or marked with the name of the contents; • display appropriate hazard warnings. The hazard warning can be any message, words, pictures or symbols that convey the hazards of the chemical(s) on the container. The label must be legible, in English (and in other languages as needed), and prominently displayed; and • show the names and addresses of the manufacturers or other responsible parties. Worker training must also be a part of your hazard communication program. OSHA requires that program records are available upon request by workers and other designated government officials. Prepared by: Angela M. Fraser, Ph.D., Associate Professor/Food Safety Specialist Department of Family and Consumer Sciences NC State University, Raleigh, NC 27695-7605 The material in this fact sheet, unless otherwise identified, is based upon work supported by the Extension Service, U.S. Department of Agriculture, under special project number 2003-51110-01715, the National Integrated Food Safety Initiative of the Integrated Research, Education, and Extension Competitive Grants Program. For more information, contact Dr. Angela Fraser at 919-515-9150 or at angela_fraser@ncsu.edu. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability through North Carolina State University, North Carolina A & T State University, U.S. Department of Agriculture, and local governments cooperating.
