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3 years ago

Which chemical change ? A.boiling B.freezing C.burning D.melting

Chemistry

2 answers:

fredd [130]3 years ago

5 0

ANSWER:

the answer is burning as it is a chemical change emaning that the substance changes chemically, the other choices are exp of physical changing meaning they stay the same substance but change physically

~batmans wife dun dun dun...aka ~serenitybella

larisa [96]3 years ago

3 0

Boiling The liquid water is being chemically changed into a gas

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What atomic or hybrid orbitals make up the pi bond between the C1 And C2 in tetrafluoroethylene, C2F4? How many sigma bonds does

schepotkina [342]

C1 has 3 sigma bonds and 1 pi bond.

3 0

3 years ago

Explain in a short sentence how you can tell if a reaction is a double replacement<br> reaction.

Monica [59]

Explanation:

In a double displacement reaction, there is an actual exchange of partners to form new compounds.

The reaction is given as shown below:

AB + CD → AD + CB

One of the following conditions serves as the driving force for a double replacement reaction:

Formation of an insoluble compound or precipitate
Formation of water or any other non-ionizing compound
Liberation of a gaseous product.

4 0

3 years ago

Is mass conserved when you burn wood?

Alex_Xolod [135]

No it is not conserved

7 0

4 years ago

A weather balloon is filled with helium that occupies a volume of 5.57 104 L at 0.995 atm and 32.0°C. After it is released, it r

Alchen [17]

6.52 × 10⁴ L. (3 sig. fig.)

<h3>Explanation</h3>

Helium is a noble gas. The interaction between two helium molecules is rather weak, which makes the gas rather "ideal."

Consider the ideal gas law:

$P\cdot V = n\cdot R\cdot T$ ,

where

$P$ is the pressure of the gas,
$V$ is the volume of the gas,
$n$ is the number of gas particles in the gas,
$R$ is the ideal gas constant, and
$T$ is the absolute temperature of the gas in degrees Kelvins.

The question is asking for the final volume $V$ of the gas. Rearrange the ideal gas equation for volume:

$V = \dfrac{n \cdot R \cdot T}{P}$ .

Both the temperature of the gas, $T$ , and the pressure on the gas changed in this process. To find the new volume of the gas, change one variable at a time.

Start with the absolute temperature of the gas:

$T_0 = (32.0 + 273.15) \;\text{K} = 305.15\;\text{K}$ ,
$T_1 = (-14.5 + 273.15) \;\text{K} = 258.65\;\text{K}$ .

The volume of the gas is proportional to its temperature if both $n$ and $P$ stay constant.

$n$ won't change unless the balloon leaks, and
consider $P$ to be constant, for calculations that include $T$ .

$V_1 = V_0 \cdot \dfrac{T_1}{T_2} = 5.57\times 10^{4}\;\text{L}\times \dfrac{258.65\;\textbf{K}}{305.15\;\textbf{K}} = 4.72122\times 10^{4}\;\text{L}$ .

Now, keep the temperature at $T_1 =258.65\;\text{K}$ and change the pressure on the gas:

$P_1 = 0.995\;\text{atm}$ ,
$P_2 = 0.720\;\text{atm}$ .

The volume of the gas is proportional to the reciprocal of its absolute temperature $\dfrac{1}{T}$ if both $n$ and $T$ stays constant. In other words,

$V_2 = V_1 \cdot\dfrac{\dfrac{1}{P_2}}{\dfrac{1}{P_1}} = V_1\cdot\dfrac{P_1}{P_2} = 4.72122\times 10^{4}\;\text{L}\times\dfrac{0.995\;\text{atm}}{0.720\;\text{atm}}=6.52\times 10^{4}\;\text{L}$

(3 sig. fig. as in the question.).

See if you get the same result if you hold $T$ constant, change $P$ , and then move on to change $T$ .

6 0

3 years ago

What is the mass of 3.20x10^23 formula units of iron (III) oxide (Fe2O3)?

yaroslaw [1]

The mass of iron (III) oxide (Fe2O3) : 85.12 g

<h3>Further explanation</h3>

Given

3.20x10²³ formula units

Required

The mass

Solution

1 mole = 6.02.10²³ particles

Can be formulated :

N = n x No

N = number of particles

n = mol

No = 6.02.10²³ = Avogadro's number

mol of Fe₂O₃ :

$\tt n=\dfrac{3.2.10^{23}}{6.02.10^{23}}=0.532$

mass of Fe₂O₃ (MW=160 g/mol)

$\tt mass=mol\times MW=0.532\times 160=85.12~g$

4 0

3 years ago