Pliz answer 1 & 2 .... I'll tag best answer brainliest .... no spamming

90 POINTSSSS!!!

Katarina [22]

Answer:

$\large \boxed{\text{-2043.96 kJ/mol}}$

Explanation:

Assume the reaction is the combustion of propane.

Word equation: propane plus oxygen produces carbon dioxide and water

Chemical eqn: C₃H₈(g) + O₂(g) ⟶ CO₂(g) + H₂O(g)

Balanced eqn: C₃H₈(g) + 5O₂(g) ⟶ 3CO₂(g) + 4H₂O(g)

(a) Table of enthalpies of formation of reactants and products

$\begin{array}{cc}\textbf{Substance} & \textbf{$\Delta_{\text{f}}$H/(kJ/mol}) \\\text{C$_{3}$H$_{8}$(g)} & -103.85 \\\text{O}_{2}\text{(g)} & 0 \\\text{CO}_{2}\text{(g)} & -393.51 \\\text{H$_{2}$O(g)} & -241.82\\\end{array}$

(b)Total enthalpies of reactants and products

$\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)\\= \text{-2147.81 kJ/mol - (-103.85 kJ/mol)}\\= \text{-2147.81 kJ/mol + 103.85 kJ/mol}\\= \textbf{-2043.96 kJ/mol}\\\text{The enthalpy change is $\large \boxed{\textbf{-2043.96 kJ/mol}}$}$

ΔᵣH° is negative, so the reaction is exothermic.

5 0

2 years ago

Someone pls pls pls help me with this question.

Arisa [49]

$\rm{\pink{\underline{\underline{\blue{REASON:-}}}}}$

⭐ Elements in which the last electron enters any one of the five d-oribitals of their respective penultimate shells are called as d-block elements .

⭐ But the last electron of Zn , Cd , Hg and Cn enters in the s-oribital of their respective ultimate shells rather than the d-oribitals of their respective penultimate shells . Therefore, these elements cannot be regarded as d-block elements .

☃️ But properties of these elements resemble to the d-block elements rather than s-block elements .

☃️ Therefore, to make the study of periodic classification of elements more rational, they are studied along with d-block elements .

✍️ Thus on the basis of properties all transition elements are d- block elements, but on the basis of electronic configuration all d -block elements are not transition elements .

3 0

3 years ago

You plan to separate a polar and a non-polar compound using normal phase column chromatography technique. Methylene chloride (CH

marissa [1.9K]

Answer:

Hexane should be used first.

Explanation:

Chromatography is a method of separating the constituents of a mixture by taking advantage of their different rates of movement in a solvent over an adsorbent medium. Chromatography is a means of separation and analysis that utilises fractional separation. It is based on the principle that if a fluid containing a number of substances is allowed to pass though an adsorbent medium, the different substances in the fluid may travel at different rates and be separated.

The rate of movement depends on the relative affinities of the constituents for the solvent and adsorbent medium. i.e solutes which are weakly adsorbed by the adsorbent medium are easily redissolved by the ascending solvent and quickly travel up the adsorbent medium. In addition to that , solutes which are very soluble in the solvent move up at a faster rate than those which are not soluble.

In column Chromatography;

A non-polar solvent should be initiated and applied first. This is because , in a column chromatography, a non-polar compound will be removed at first then later polar compound.

Assuming a polar compound is used first, the polar compounds will be removed alongside with all the non-polar compounds.

From the two Compounds given;

We know that :

Hexane is a non-polar compound and Methylene chloride is a polar compound. As such, Hexane should be used first.

3 0

2 years ago

A glass marble is rubbed against a piece of silk. As a result the piece of fabric acquires extra electrons. What happens to the

Natalija [7]

Answer:

There was an electron transfer where the marble has lost the same amount of electrons (being positively charged) that the piece of silk has gained (being negatively charged).

Explanation:

As a result of this transfer of electrons and the charges induced in the objects they will attract.

When a body is endowed with electrical properties, that is, it acquires electrical charges, it is said to have been electrified.

Electrification is one of the phenomena that studies electrostatics.

To explain how static electricity originates, we must consider that matter is made of atoms, and atoms of charged particles, a nucleus surrounded by a cloud of electrons. Normally, matter is neutral (not electrified), it has the same number of positive and negative charges.

Some atoms are easier to lose their electrons than others. If a material tends to lose some of its electrons when it comes into contact with another, it is said to be more positive in the Triboelectric series. If a material tends to capture electrons when it comes into contact with another material, that material is more negative in the triboelectric series.

4 0

2 years ago

Read 2 more answers

Which units are used to measure both velocity and speed? Select three options

Ede4ka [16]

Answer and Explanation:

The options aren't listed in your question, but here are some units that are regularly and normally used (in the classroom and in the outside world):

(The SI unit of distance and displacement is the meter. The SI unit of time is the second.)

Meters per Second (m/s)

kilometers per hour (km/hr)

kilometers per second (km/sec)

To find the average speed, you do distance divided by time.

To find the average velocity, you do the final position minus the initial position, divided by the final time minus the initial time.

#teamtrees #PAW (Plant And Water)

I hope this helps!

8 0

2 years ago

Pliz answer 1 & 2 .... I'll tag best answer brainliest .... no spamming ​

Pliz answer 1 & 2 .... I'll tag best answer brainliest .... no spamming