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3 years ago

How does ur body maintain constant tempature on a hot day?

2 answers:

8 0

It knows that when water evaporates, it carries heat energy away with it.
So your body puts some water out on your skin, and hopes that it will
evaporate. We call that "perspiring" or "sweating".

Romashka [77]3 years ago

7 0

Answer:

your skin opens up

Explanation:

the pores i your skin opens up and let the water (sweat) out to help cool down your body.

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Ice floats on water. For most other substances however, the solid sinks in the liquid. Classify each of these statements as true

Brut [27]

Answer:

See explanation below

Explanation:

Water has the anomality of having the solid less dense than the liquid state. The reason for this is that the hydrogen bonds in the solid ice forces the molecule to occupy more room to properly have the stability afforded by the hydrogen bonds. That is the reason why ice floats on water.

The other interesting consequence of this anomality is that the slope of the solid/liquid phase boundary is negative since at higher pressures the ice can be changed to its liquid phase which can be seen from the negative slope of the solid/liquid boundary.

A) True

B) False

C) False

D) True

E) False

F) True close up to 4 ºC when the water molecules start to behave like other liquids, that is the density of the liquid decreases.

G) True

H) True ( repeated question)

8 0

3 years ago

How many kilojoules of heat will be released when exactly 1 mole of iron, Fe, is burned to form Fe2O3 at standard state condaiti

Diano4ka-milaya [45]

Answer:

412.1kJ

Explanation:

For the reaction , from the question -

4Fe (s) + 3O₂ (g) → 2Fe₂O₃ (s)

Δ Hrxn = Δ H°f (products) - Δ H°f (reactants)

In case the compound is in its standard state , enthalphy of formation is zero

Hence ,

for the above reaction ,

ΔHrxn =( 2 * Δ H° (Fe₂O₃ )) - [ ( 4 *Δ H° Fe ) + (3 * Δ H° O₂ )]

The value for Δ H°(Fe₂O₃ ) = - 824.2kJ/mol

Δ H° Fe = 0

Δ H° O₂ = 0

Putting in the above equation ,

ΔH rxn = ( 2 * Δ H° (Fe₂O₃ )) - 0

ΔHrxn = 2× - 824.2 kJ / mol = - 1648.4 kJ/mol

- 1648.4 kJ/mol , this much heat is released by the buring of 4 mol of Fe.

Hence ,

for 1 mol of Fe ,

- 1648.4 kJ/mol / 4 = 412.1kJ

8 0

3 years ago

If you have 120. mL of a 0.100 M TES buffer at pH 7.55 and you add 3.00 mL of 1.00 M HCl, what will be the new pH? (The pKa of T

Simora [160]

Answer:

The new pH after adding HCl is 7.07

Explanation:

The formula for calculating pH of a buffer is

pH = pKa + log([Conjugate base]/[Acid])

<u>Before adding HCl,</u>

7.55 = 7.55 + log([Conjugate base]/[Acid])

⇔ log([Conjugate base]/[Acid]) = 0

⇔ [Conjugate base] = [Acid] = 1/2 x 0.100 = 0.05 M

⇒ Mole of Conjugate base = Mole of Acid = 0.05 M x 0.12 mL = 0.006 mol

<u>After adding HCl (3.00 mL, 1.00 M)</u>

⇒ Mole of HCl = 0.003 x 1 = 0.003 mol)

New volume solution is 120 m L+ 3 mL = 123 mL

HCl is a strong acid, it will convert the conjugate base to acid form, or we can express

Mole of new Conjugate base = 0.006 - 0.003 = 0.003 mol

⇒ Concentration = 0.003/0.123 M

Mole of new Acid form = 0.006 + 0.003 = 0.009 mol

⇒ Concentration = 0.009/0.123 M

Use the formula

pH = pKa + log([Conjugate base]/[Acid])

= 7.55 + log(0.003 / 0.009) = 7.07

8 0

3 years ago

A simple machine produces 25 joules of output work for every 50 joules of input work . What is the efficiency of this machine ?

nataly862011 [7]

2:1, output is half the input

8 0

4 years ago

Is the Sun bigger and brighter than Betelgeuse?

Naddik [55]

Answer:

Explanation:

Betelgeuse has a diameter around 700 times the size of our sun…. like possibly as far as the orbit of Jupiter. It is known as a red supergiant and around 100,000 times brighter than our sun. Betelgeuse is at the very end of its life.

5 0

3 years ago