Chemistry, 16.03.2020 16:32 paralaw61772

A student conducted a scientific investigation on the magnetic properties of iron. She used a magnet to try to pick up iron nails. After making several observations, which question can she answer? Which part of a magnet is strongest at attracting iron? How fast does iron lose its magnetism? What is the importance of studying the magnetic field of a magnet? How does the color of iron change with exposure to air?

Answers: 2

Show answers

Answers

Answer from: Quest

3 1/4 %

explanation:

Answer from: Quest

The grandmother cell is a hypothetical neuronthat represents a complex but specific concept or object.[1] it activates when a person "sees, hears, or otherwise sensibly discriminates"[2] a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the gnostic neuron, was proposed two years later

Answer from: Quest

Iam pretty sure that the answer is d

Answer from: Quest

the missing options are :

(1) lower boiling point and a lower freezing point(2) lower boiling point and a higher freezing point(3) higher boiling point and a lower freezing point(4) higher boiling point and a higher freezing point

answer : the correct answer is option (3) higher boiling point and a lower freezing point

explanation :

when a non volatile solute is added to a solvent like water, it results in elevation of boiling point.

let us find the increase in boiling point of water when cacl₂ is added to water to make a solution of 1 m

step 1 : find molality of the solution

let us assume we have 1 l of solution.

$m = \frac{moles (solute)}{l ( solution)}$

$1 m = \frac{moles (cacl_{2})}{1 l }= 1 mol cacl_{2}$

let us convert this to grams of cacl₂.

molar mass of cacl2 is 111 g/mol

grams of cacl₂ = $1 mol \times \frac{111g}{mol} = 111 g cacl_{2}$

mass of solute = 111 g

assuming density of solution same as water which is 1g/ml we have ,

mass of solution = density * volume

mass of solution = $\frac{1g}{ml} \times 1000 ml = 1000 g$

mass of solution = mass of solvent + mass of solute

mass of solute = 1000g - 111g

mass of solute 889 g = 0.889 kg

the molality of the solution can be calculated as

$molality = \frac{mol (solute)}{kg ( solvent)}$

$molality = \frac{1mol}{0.889kg}$

molality = 1.12 m

step 2 : find boiling point elevation.

the elevation in boiling point is calculated as

$\bigtriangleup t_{b} = i \times k_{b} \times m$

here δtb = boiling point elevation

i = vant hoff factor which is the number of ions formed by the solute .

cacl₂ dissociates as $cacl_{2} \rightarrow ca^{2+} + 2 cl^{-}$

it forms 3 ions . therefore,

i = 3

m = molality which is 1.12 m

kb is constant for a given solvent. for water it is 0.512

$\bigtriangleup t_{b} = 3 \times 0.512 \times 1.12$

$\bigtriangleup t_{b} = 1.7$

the boiling point of water increases by 1.7 °c

step 3: find freezing point depression.

when a non volatile solute is added to water, it results in decrease in freezing point.

the formula to find freezing point depression is

$\bigtriangleup t_{f} = i \times k_{f} \times m$

kf is constant for water and its value is 1.86

$\bigtriangleup t_{f} = 3 \times 1.86 \times 1.12$

$\bigtriangleup t_{f} = 6.2$

the freezing point of water decreases by 6.2 °c

therefore we can say that, the solution will have a higher boiling point and a lower freezing point

Another question on Chemistry

Chemistry, 21.06.2019 19:30

Which answer lists the fundamental forces in order from strongest to weakest

Answers: 1

Answer

Chemistry, 21.06.2019 22:30

Write the symbol for every chemical element that has atomic number greater than 3 and atomic mass less than 12.0 u.

Answers: 1

Answer

Chemistry, 22.06.2019 09:00

Astudent is asked to identify and element that is pale yellow brittle solid and does not conduct electricity. at which location in this periodic table would the element most likely be found?

Answers: 2

Answer

Chemistry, 22.06.2019 10:10

Stage in which a typical star has completely stopped fusion

Answers: 1

Answer

You know the right answer?

A student conducted a scientific investigation on the magnetic properties of iron. She used a magnet...

Questions