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vodomira [7]
4 years ago
9

Rain puddle drying up, chemical or physical change

Chemistry
1 answer:
Volgvan4 years ago
3 0
Physical change because it's getting smaller as it disappears.
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What is a face atom?
gavmur [86]

Answer:

Explanation:

An atom on a face is shared by two unit cells, so only half of the atom belongs to each of these cells. An atom on an edge is shared by four unit cells, and an atom on a corner is shared by eight unit cells.

3 0
3 years ago
Natasha and Reanna observe a large airplane in the troposphere. Which experimental setup below would best determine how changing
snow_lady [41]

Answer:

i am pretty sure the answer is a

Explanation: because the airplane's flight time has to be the independent variable for it to affect the dependent variable that is the speed of how fast the airplane is going.

8 0
3 years ago
Read 2 more answers
Calculate the following:
d1i1m1o1n [39]

Answer:

Explanation:

1) Given data:

Number of moles of lead = 4.3×10⁻³ mol

Mass of lead = ?

Solution:

Mass = number of moles × molar mass

Molar mass of lead = 207.2 g/mol

Mass = 4.3×10⁻³ mol × 207.2 g/mol

Mass =  890.96 g

2) Given data:

Number of atoms of antimony = 3.8×10²² atoms

Mass of antimony = ?

Solution:

1 mole contain 6.022 ×10²³ atoms

3.8×10²² atoms × 1 mol / 6.022 ×10²³ atoms

0.63×10⁻¹ mol

0.063 mol

Mass = number of moles × molar mass

Molar mass of lead = 121.76 g/mol

Mass = 0.063 mol ×  121.76 g/mol

Mass =  7.67 g

3) Given data:

Mass of tungsten = 15.5 Kg (15.5 kg × 1000 g/ 1kg = 15500 g)

Number of atoms = ?

Solution:

Number of moles of tungsten:

Number of moles = mass/molar mass

Number of moles = 15500 g / 183.84 g/mol

Number of moles = 84.3 mol

1 mole contain 6.022 ×10²³ atoms

84.3 mol  × 6.022 ×10²³ atoms / 1mol

507.65 ×10²³ atoms

8 0
3 years ago
What is the name of this molecule?<br><br> H3C - C ≡ C - CH3<br><br> Answer: 1,2,3, or 4-butyne?
Semenov [28]

Explanation:

The given molecule is

H3C - C ≡ C - CH3

The numbering order is shown below:

H3C - C ≡ C - CH3

    1     2     3     4

So, the alkyne group is in the second position.

The carbon chain has four carbons.

Hence, the IUPAC name of the given compound is:

2-butyne.

8 0
3 years ago
A mysterious white powder could be powdered sugar (C12H22O11), cocaine (C17H21NO4), codeine (C18H21NO3), norfenefrine (C8H11NO2)
konstantin123 [22]

Answer: norfenefrine (C_8H_{11}NO_2)

Explanation:

Depression in freezing point is given by:

\Delta T_f=i\times K_f\times m

\Delta T_f=T_f^0-T_f=(-114.6-(-115.5)^0C=0.9^0C = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte)

K_f = freezing point constant = 1.99^0C/m

m= molality

\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}}\times \text{weight of solvent in kg}}

Weight of solvent (ethanol)= density\times volume=0.789g/cm^3\times 1.50cm^3=1.18g=1.18\times 10^{-3}kg

Molar mass of unknown non electrolyte = M g/mol

Mass of unknown non electrolyte added = 82 mg = 0.082 g (1g=1000mg)

0.9=1\times 1.99\times \frac{0.082g}{M g/mol\times 1.18\times 10^{-3}}kg}

M=154g/mol

The molecular mass of norfenefrine (C_8H_{11}NO_2) is near to 154 and thus the identity of the white powder is norfenefrine .

4 0
3 years ago
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