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3 years ago

False or true A phase change is an Indicator of a chemical reaction.And why?

Chemistry

2 answers:

Katena32 [7]3 years ago

6 0

Answer:

False

Explanation:

A phase change does not involve changing the identity or makeup of that species. When you take solid ice and melt it (add enough energy to it) it changes to water, which is now a liquid. A chemical change would involve reactions taking place that would change the whole identity of that species.

Lerok [7]3 years ago

3 0

Answer:

False

Explanation:

A phase change does not involve changing the identity or makeup of that species. When you take solid ice and melt it (add enough energy to it) it changes to water, which is now a liquid. ... A chemical change would involve reactions taking place that would change the whole identity of that species.

I hope this helps!

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How many moles of Fe2O3 are in 203 g of the compound?

ruslelena [56]

The equation is :
moles=mass/molar mass
so, the mass is 203 and molar mass is 159.69
You divide the 203 by 156.69 as the equation shows
so the moles is 1.27 mol.

6 0

3 years ago

My swimming pool is rectangular (16 feet by 34 feet) and has a depth of 6 feet. Lets imagine that my pool water is full to the t

Reil [10]

Answer:

Number of moles of photons required = 5.04 × 10⁴ moles

Explanation:

The energy of a photon can be calculated from Planck's equation E = hc/λ

Where h = 6.63 × 10-³⁴ Js and c, the velocity of light = 3.0 × 10⁸ m/s

Energy of one mole of photons = N₀ × hc/λ

wavelength of photon, λ = 520 nm = 5.20 × 10-⁷ m

Energy of one mole of photons = 6.02 × 10²³ × 6.63 × 10−³⁴ × 3 × 10⁸/5.20 × 10-⁷

Energy of one mole of photons = 2.30 × 10⁵ J/mol

Energy required to raise the temperature of a given mass of a substance, E = mcΔT

Where m is mass of substance, c is specific heat capacity, ΔT is temperature difference

Mass ofnwternin the pool = volume × density

Volume of water = Volume of swimming pool

Volume of water = 16 × 34 × 6 ft³ = 3264 ft³

1 ft³ = 28316.8 cm³; 3264 ft³ = 28316.8 × 3264 = 92426035.2 cm³

Density of water = 1 g/cm³

Mass of water = 92426035.2 cm³ × 1 g/cm³ = 92426035.2g

ΔT = 80°C - 50°C = 30°C, c = 4.18 J/g/K

Energy required to raise 92426035.2 g water by 30° C = 92426035.2 × 4.18 × 30

Energy required = 1.16 × 10¹⁰ J

Hence, number of moles of photons required = 1.16 × 10¹⁰ J/2.30 × 10⁵ J/mol

Number of moles of photons required = 5.04 × 10⁴ moles

5 0

3 years ago

Why should you always condition a buret before running a titration?.

Alex Ar [27]

Answer:

Conditioning two or three times will insure that the concentration of titrant is not changed by a stray drop of water.

Explanation:

"Check the tip of the buret for an air bubble. To remove an air bubble, whack the side of the buret tip while solution is flowing".

5 0

2 years ago

Menthol (FW = 156.3 g/mol), the strong-smelling substance in many cough drops, is a compound of carbon, hydrogen, and oxygen. Wh

Alisiya [41]

Answer: the molecular formula is C10H20O

Explanation:Please see attachment for explanation

7 0

3 years ago

Hydroxyl radicals react with and eliminate many atmospheric pollutants. However, the hydroxyl radical does not clean up everythi

Nesterboy [21]

Answer:

ΔHreaction = 263.15 kJ/mol

Explanation:

The reaction is as follow:

OH + CF₂Cl₂ → HOF + CFCl₂

You need to calculate the enthalpy of reaction and for this it is necessary to know the standard enthalpies for each of the compounds. These enthalpies are as follows and can be found in your textbook or on the Internet.

ΔHreaction = ∑ΔHproducts - ∑ΔHreactants

$delta(H)_{reaction} =((1*(-97.8)+(1*(-92))-((1*39)+(1*(-491.15))=263.15kJ/mol$

7 0

3 years ago