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3 years ago

HELP ASAP PLEASE!!!

Chemistry

1 answer:

charle [14.2K]3 years ago

7 0

Answer 1:
Correct Answer: Option A i.e. The temperature stays constant for a while, then rises (A).

Reason:
At 0 oC, H2O exist in dual state (solid and liquid) i.e. there exist an equilibrium between ice and water. Hence, when the heat is supplied, it is initially used to bring about phase transformation from solid to liquid state. During this time, temperature remains constant. Once the phase transformation has occurred, heat is utilized for increasing the temperature of system i.e. water.
.......................................................................................................................

Answer 2:
Correct Answer: Option B) At first, the energy supplied goes into overcoming attractive forces in the solid. 
Reason:
In the present case, initially the energy supplied goes into overcoming attractive forces in the solid. Once the ice is converted into water, it now exist in single phase i.e .liquid. Hence, now when further heat is supplied to the system, it is used only for increasing the temperature of system.

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What happens when liquid magma is cooled

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Suppose 0.981 g of iron (II) iodide is dissolved in 150. mL of a 35.0 m M aqueous solution of silver nitrate. Calculate the fina

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Answer:

Final molarity of iodide ion C(I-) = 0.0143M

Explanation:

n = (m(FeI(2)))/(M(FeI(2))

Molar mass of FeI(3) = 55.85+(127 x 2) = 309.85g/mol

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n(AgNO3) = C(AgNO3) x V(solution)

= 0.035 x 0.15 = 0.00525 mol

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So, n(FeI(3)) excess = 0.00525 - 0.0031 = 0.00215mol

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3 years ago

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4 years ago

Read 2 more answers

How many atoms are in 25.00 g of B.

iren2701 [21]

Answer:

$\boxed {\boxed {\sf 1.393 *10^{24} \ atoms \ B}}$

Explanation:

1. Convert Grams to Moles

Use the molar mass (found on the Periodic Table) to convert from grams to moles.

Boron (B): 10.81 g/mol

Use this value as a ratio.

$\frac {10.81 \ g \ B }{1 \ mol \ B}$

Multiply by the given number of grams.

$25.00 \ g \ B *\frac {10.81 \ g \ B }{1 \ mol \ B}$

Flip the ratio so the grams of boron cancel out.

$25.00 \ g \ B *\frac {1 \ mol \ B }{10.81 \ g \ B}$

$25.00 *\frac {1 \ mol \ B }{10.81 }$

$\frac {25.00 \ mol \ B }{10.81 }=2.312673451 \ mol \ B$

2. Convert Moles to Atoms

We use Avogadro's Number, 6.02*10²³: the number of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, the particles are atoms of boron.

$\frac {6.02*10^{23} \ atoms \ B} {1 \ mol \ B}$

Multiply by the number of moles we calculated.

$2.312673451 \ mol \ B *\frac {6.02*10^{23} \ atoms \ B} {1 \ mol \ B}$

The moles of boron cancel.

$2.312673451 *\frac {6.02*10^{23} \ atoms \ B} {1 }$

$2.312673451 *6.02*10^{23} \ atoms \ B} =1.39269195*10^{24} \ atoms \ B$

The original value of grams has 4 significant figures, so our answer should have the same. For the number we calculated, that is the thousandth place.

$1.392\underline69195*10^{24} \ atoms \ B$