Why is it important to offer evidence to support statements about experiments?

How many kj of heat are needed to completely melt 32.3 g of h2o, given that the water is at its melting point? the heat of fusio

timurjin [86]

Answer: fourth option, 10.8 kJ

Explanation:

The heat of fusion, also named latent heat of fusion, is the amount of heat energy required to change the state of a substance from solid to liquid (at constant pressure).

The data of the heat of fusions of the substances are reported in tables and they can be shown either per mole or per gram of substance.

In this case we have that the heat of fusion for water is reported per mole: 6.02 kJ/mole.

The formula to calculate how many kJ of heat (total heat) are needed to completely melt 32.3 g of water, given that the water is at its melting point is:

Heat = number of moles × heat of fusion

The calculations are:

number of moles = mass / molar mass

number of moles = 32.3 g / 18.015 g/mol = 1.79 mol

Heat = 1.79 mol × 6.02 kJ / mol = 10.8 kJ ← answer

5 0

3 years ago

Read 2 more answers

Enter the atomic symbol, including mass number and atomic number, for iodine-130.

WINSTONCH [101]

Answer: The atomic symbol of the given element is $_{53}^{130}\textrm{I}$

Explanation:

The general isotopic representation of an element is given as: $_Z^A\textrm{X}$

where,

Z represents the atomic number of the element

A represents the mass number of the element

X represents the symbol of an element

For the given isotope: 130-iodine

Mass number = 130

Atomic number = 53

Hence, the atomic symbol of the given element is $_{53}^{130}\textrm{I}$

6 0

3 years ago

What is the identity of the element, and how many neutrons does it have? An elements most stable ion forms an ionic compound wit

Pani-rosa [81]

Answer:

B. CA, 14

Explanation:

Atoms of elements contain small particles known as electrons, neutrons, and protons. The nucleus of an atom is made up of neutrons and protons which are at the center of the atom. Electrons on the other hand surrounds the nucleus. Electron has negative charge while proton has a positive charge. The number of neutrons is equivalent to the number of protons . In addition, the number of protons is equal to mass number minus the number of electrons.

For the compound $XCl_{2}$ , it can be broken down into $X^{2+}$ and $2Cl^{-}$ . Its ion has a mass of 34 and 18 electrons which means it has already lost 2 electrons.

Therefore:

For the given element, the number of electrons is 18+2 = 20 electrons.

The number of protons = 34 - 20 = 14.

And the number of neutrons is 14.

Only option B has the correct answer.

6 0

3 years ago

If the freezing point of the solution had been incorrectly read 0.3 °C lower than the true freezing point, would the calculated

Dovator [93]

Answer : The molar mass of the solute would be low.

Explanation :

Formula used for depression in freezing point is:

$\Delta T_f=i\times K_f\times m\\\\T^o-T_s=i\times K_f\times\frac{w_b}{M_b}\times w_a}$

where,

$\Delta T_f$ = change in freezing point

$\Delta T_s$ = freezing point of solution

$\Delta T^o$ = freezing point of water

i = Van't Hoff factor

$K_f$ = freezing point constant

m = molality

$w_b$ = mass of solute

$w_a$ = mass of solvent

$M_b$ = molar mass of solute

From the formula we conclude that, when the freezing point of the solution read incorrectly that is freezing point of the solution is lower than the true freezing point then this means that change in freezing point would be high and the molar mass of the solute would be low.

Hence, the molar mass of the solute would be low.

6 0

3 years ago

What is unusual about solid water compared to solids of other materials?

fomenos

Solid water is completely clear

3 0

3 years ago