why does the temperature of water affect the strength of tea?
820130
Brewing the perfect cup of tea \n\n\n-antioxidants break down fast so fresh brewed is best \n-tea made from loose leaves has more antioxidants than tea bags which tend to have lower quality powdered leaves \n-a timer for getting exact infusion times, \n-infuser for loose-leaf tea, \n-teaspoon for measuring tea, \n-instant read thermometer to check water temperature \n-small saucer for holding used tea bag \n1.  Begin with fresh, cold good-tasting water.  Let water run to incorporate more oxygen.  Filtered is best because the process removes chemical tastes.  Distilled may be too purified and produce a flat taste.  Chlorine in tap water can lower antioxidant levels if it is not brought to a boil first. \n\n2.  In a tea kettle, bring water just to a boil to properly oxygenate it.  Over-boiling drives off oxygen. \n\n3.  Pour some on the hot water into the teapot to warm it, discard the water.  Its okay to use hot tap water for preheating.  Water temperature may drop several degrees in poured into a cold cup/teapot and decrease the flavor extraction from the tea.  You can use your saucer to cover the cup to retain the heat while brewing\n\n\n4.  Add tea leaves to pot, or use infuser.  How much tea is a matter of taste, but a good rule of thumb is about 1tsp per 1c tea plus one for the pot.  Pour hot water over the tea leaves immediately for black tea or let it cool to proper temp for other types of tea.  \n\n\n5.  Let the leaves steep.  Watch the clock not the color. \n\n·        Oolongs need just 1-2 minutes at between 185-195F \n\n·        Green tea needs only to be steeped 2-3 minutes at 165-180F.  Lower temperature helps protect against bitter taste.  However, longer steeping will extract more antioxidants. \n\n·        Most black teas should be steeped right at boiling (212F) for 3-5 minutes. \n\n·        The longer you steep, the more bitter your tea will be.  Never steep more than 5 minutes except for white tea which can be infused for 5-7 minutes and herbal which requires 10-20minutes to extract flavor.  Add more tea leaves for a stronger brew. \n\n·        If using loose tea leaves, make sure your leaves have room to “unfurl”.
45614
It's to do with humidity of the air. If you watch the weather report you may notice that humidity is expressed as a percentage. This is how 'full' the air is with water vapour. If the air is nearly empty (low humidity) then water will evaporate more quickly. If the air is full (high humidity) the water will evaporate more slowly (it may even receive more water from the air!).\n\nHere is the key: hot air can hold MORE water than cold air. So even if say a gallon of water is the most that some amount of air can hold, if you the air up the air will no longer be 'full' (for example it might be only 70% full, hence 70% humidity).\n\nThis is not a complete answer as I do not know everything about it. It's pretty advanced for 5th grade (I learnt about it in the 11th grade!). For more information look up EQUILIBRIUM in chemistry.
149250
When the temperature of the water in the bottle approaches 32 degrees farehheit (the temperature where water freezes) is expands.  This pre-freeze expansion can rupture most nearly full containers.\n\nThe one good thing about this unusual physical phenomenon is that this is the reason that tce forms on the tops of lake or pond water.  This enables people to skate on the ponds in winter time.  The top layer of water freezes, while the lower water stays in a liquid form.
141535
The Climate.Pressure increases if temperature increases and volume stays the same. This is because the molecules are moving faster and colliding harder with the sides of the container. The greater the mass of air in the container, the greater the number of molecules in the container and the higher its density. The air molecules in the container collide against the sides of the container, so the more of them there are colliding against sides of the container the greater the overall force on the sides of the container. If the temperature is high enough the moisture is vapor or steam and if the moisture doesn't condense on the sides of the container then the moisture molecules are also colliding with the side of the container. On the other hand, if the air in the container is cool enough that the moisture does condense then the moisture is no longer exerting outward force on the container (or at least there's much less of it still moving around as vapor and colliding with the sides of the container).\n\nWhen you're talking about a body of water with gas (carbon dioxide) and sugar in it, like Coke, if the bottle is still closed then you have a volume of air above the soda that exerts enough force on the soda to prevent the gas from coming out of the soda at all until you open the bottle. Once the bottle is open, think about surface tension. That's the reason the carbon dioxide is released slowly when you open the bottle. If you disrupt the surface tension the gas can release all at once.
664364
There's actually a number of reasons why water does that. Yes, cooler or warmer water can come in and make water differ in temperature in different parts of the body of water. Another reason is that water takes a lot longer to cool or heat than many other things like the earth. The depth of the water makes an impact also. The sun's rays passing through the water faster at different depths heat water when it's not as deep.
15822
It mainly depends on the pressure (if we are talking about pure water). The higher the pressure, the higher the boiling point - it can be much lower (ex. high in the mountains) or much higher than 100 degrees C (the boiling point under normal atmospheric pressure). If we don't talk about pure water, then adding other chemicals (for example, table salt - sodium chloride) can raise the boiling point as well.
168436
Water boils at 212 F.  The hotter the water, the less energy is needed to achieve this temp.  Of course pressure counts too.  Higher altitudes require different amounts of energy.  I think this is Doyles law.  Chem 101 would be a good class to learn this type of thing.  Also the purity of the water makes a difference.  The less pure the water (minreals, other impurities with lessen the amount of energy needed to achieve boiling temp.
279818
Temperature DOES affect the amount of salt that can be dissolved in a liquid.  Generally the higher the temperature, the more solute can be dissolved
711128
Some of the water soluble compound present in the tea leaves dissolve in the water, any ionic compounds also dissociate.
21135
water on the ground, in oceans, lakes, etc. has enough energy to evaporate a little bit (all liquids have a "vapor pressure," which is higher the hotter it is).  eventually, there is too much water in the air at whatever air temperature it is, so the water re-liquifies and falls.  this can commonly happen when a warm front (warm air holds lots of water) is cooled by a cold front.
557600
Water is one of the few substances that expands as it freezes.  From 4 degrees Celsius down to 0 degrees water expands and as a result the frozen solid form is less dense than the liquid form and that is why ice floats.\nThe water in the soft drink expands and the can cannot hold the increase in volume.
154119
Water is a Newtonian fluid, meaning its shear stress is linearly proportional to rate of shearing strain. Agitation will not affect its viscosity. Pressures will not affect it either unless they are extremely high.\n\nThe viscosity of water generally decreases as temperature increases. Water at 32ºF has an absolute viscosity of 1.794 cp (centipoise). At 200ºF, its viscosity will have decreased to .305 cp.\n\nThis means that water will flow slightly more easily at higher temperatures.\n\nFor some mathematical models, check out this link:\n\nhttp://en.wikipedia.org/wiki/Temperature_dependence_of_liquid_viscosity
587903
Steam isn't "hotter", it's still at 100°.  What it has though is more heat energy in it kg for kg.  The extra energy is the heat of vaporization and it's the reason the steam takes up so much more volume than the water at the same temperature.  The water molecules have the same average kenetic energy - temperature - but they occupy much less space.
480166
If you have an equal volume of hot and cold water the cold water will be heavier.  This is because when you heat up a substance it become less dense, and in general when you cool down a substance it becomes more dense.\n\nThe exception to the rule is water though.  Water is most dense at 3 degrees cesius, after that it start to take a crystalin form and when it freezes actualy expands.  \n\nso long as you are not saying that the cold water is 1 degree and the hot water is 3, then the cold water will be heavier\n\n\nBut remeber it is not by much in any case
383320
the idea isn't that water can't heat up when it boils at low pressure, but that it doesn't have to. no matter what temperature something is, its molecules are moving somewhat, and some of them escape as a gas. also, any gas always is condensing into a liquid or solid. when pressure and tempurature are constant, these processes reach equilibrium where they cancel each other out. at high temperature, more gasses escape, and at low pressure, less gases return to liquid. so at somewhat low temperature and relativly lower pressure, even though few gases relatively escape, even fewer return to liquid, so the net effect is that the liquid evaporates at low temperature. if the temperature were raised, it would boil even faster.
124074
In short: Any solution will boil at a higher temperature than the pure solvent. \nBoiling point elevation is a colligative property. Use the formula provided by emilyrose. The addition of salt to water causes vapor pressure reduction of the water. This is because the addition of a non-volatile solute causes a reduction in the surface area available to water molecules, reducing the likelihood of evaporation. This vapor pressure lowering is described by Raoults Law (see link).\nInterestingly, if you have a salt solution, and you heat it till it boils, as the water evaporates, the boiling temperature of the solution will continuously increase, because its molality increases. Please see the link below for a more detailed discussion.
938890
The reason why the temperature does not change even though more heat is being added to the ice or water is that heat is needed to break the hydrogen bonds in ice to allow the phase change, and heat is needed to break the surface tension of the liquid to make water vapor.  Until all the bonds are broken there cannot be any increase in temperature.  Remember that temperature is just a macro measurement of the kinetic energy of the moving molecules.