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3 years ago

An udentified substance, Y, was thought to be one of the following three compounds.

1 answer:

7 0

This is more logic deduction than having learnt this, but i would think Y = B because it hasnt affected the melting point, implying its the same substance? hope this helps a bit :)

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Pure nitrobenzene freezes at 5.67 C. When 1.0g of ethanol (C2H6O) is mixed with 20.0g nitrobenzene, the freeze point drops to –0

sukhopar [10]

Answer: The freezing-point depression constant (Kf) of nitrobenzene is $5.7^0C/m$

Explanation:

Depression in freezing point is given by:

$\Delta T_f=i\times K_f\times m$

$\Delta T_f=T_f^0-T_f=(5.67-(-0.53)^0C=6.2^0C$ = Depression in freezing point

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

$K_f$ = freezing point constant = ?

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 = 20 g = 0.02 kg

mass of solute (ethanol) = 1.0 g

Molar mass of ethanol = 46 g/mol

$6.2=1\times K_f\times \frac{1.0g}{46g/mol\times 0.02kg}$

$K_f=5.7^0C/m$

Thus freezing-point depression constant (Kf) of nitrobenzene is $5.7^0C/m$

5 0

3 years ago

If 4.35 KJ of

joja [24]

4.186 Joules equals 1 cal.
1 cal is the amount of energy needed to increase in 1ºC the temperature of 1 gram of water. If we add to 15.5 grams of water 4350 Joules, we are adding approximately 1039.2 cal. (4350÷4.186≈1039.2)
This energy though is being divided by all the gram in the water. 1039.2cal÷15.5g≈67.0cal/g
4.35kJ would increase the water's temperature in approximately 67ºC, putting it at 72ºC. The state would remain the same - liquid - though much closer to boil.

4 0

3 years ago

A reaction proceeds with 2.72 moles of magnesium chlorate and 3.14 moles of sodium hydroxide. This is the equation of the reacti

TiliK225 [7]

Mg(ClO3)2 + 2NaOH → Mg(OH)2 + 2NaClO3.

This is about as hard a question as you can get in beginning chemistry. You have to figure out which chemical between the two reactants is the LEAST number of moles before you can do anything about the products. Read that sentence over again carefully and keep in mind what least means. It's the key to the entire question.

For every mole of Mg(ClO3)2 you need two moles of NaOH. That's what the balanced equation tells you. The big number on the left of the chemical is where I'm getting 1 to 2. One is in front of Mg(ClO3)2 and 2 is to the left of NaOH

So you have 2.72 moles of Mg(ClO3)2. You would need to have 2.72*2 moles of NaOH which is 5.44 moles of NaOH. Do you have enough NaOH. (I should hear a resounding NO.) So the limiting reactant is NaOH. You only have 3.14 moles of NaOH. Now you can start getting the answer to the question

You now need to set up the same ratio for the Mg(OH)2

For every 2 moles of NaOH you get 1 mole of Mg(OH)2. The proportion is

NaOH/Mg(OH)2 = 2/1

NaOH = 3.14 moles

3.14 / Mg(OH)2 = 2/1 Cross multiply

3.14 = 2 * Mg(OH)2 Divide by 2

3.14/2 = Mg(OH)2 Combine the left

1.57 = Mg(OH)2 Answer

============

I'll let you work through the second blank. I'm not completely heartless so I'll tell you that the ratio is 1:1 and that the answer should be 3.14

============

Answer Box one = 1.57

Answer Box Two = 3.14

3 0

3 years ago

Read 2 more answers

what sentence describes all atoms of one element A. They have the same number of isotopes B. They have the same properties C. Th

Daniel [21]

Answer:

C. They have the same number of protons.

Explanation:

Even though in isotopes, there's uneven number of neutrons, there's always same number of protons.

Hope it helps.

6 0

3 years ago

Give the term for the temperature at which the gas and liquid phases form a supercritical fluid:__________

Ber [7]

Answer: option C. Critical temperature

Explanation:

5 0

4 years ago