Which of the following statements best provides evidence of the big bang theory?

When 2.714 g of AX (s) dissolves in 127.4 g of water in a coffee-cup calorimeter the temperature rises from 23.3 °C to 37.1 °C.

MakcuM [25]

Answer : The enthalpy change for the solution is 166.34 kJ/mol

Explanation :

First we have to calculate the enthalpy change of the reaction.

Formula used :

$\Delta H=mC\Delta T\\\\\Delta H=mC(T_2-T_1)$

where,

$\Delta H$ = change in enthalpy = ?

C = heat capacity of water = $4.18J/g.K$

m = total mass of sample = 2.174 + 127.4 = 129.6 g

$T_1$ = initial temperature = $23^oC=273+23=296K$

$T_2$ = final temperature = $37.1^oC=273+37.1=310.1K$

Now put all the given values in the above expression, we get:

$\Delta H=mC(T_2-T_1)$

$\Delta H=129.6g\times 4.18J/g.K\times (310.1-296)K=7638.36J$

Now we have to calculate the moles of AX added to water.

$\text{ Moles of }AX=\frac{\text{ Mass of }AX}{\text{ Molar mass of }AX}=\frac{2.714g}{59.1097g/mole}=0.04592moles$

Now we have to calculate the enthalpy change for the solution.

As, 0.04592 moles releases heat = 7638.36 J

So, 1 moles releases heat = $\frac{7638.36}{0.04592}=166340.59J=166.34kJ$

Therefore, the enthalpy change for the solution is 166.34 kJ/mol

7 0

3 years ago

What is the boiling point for water in degrees celsius?

soldier1979 [14.2K]

Answer:

<h2>100°C is the boiling point of water in degrees Celsius</h2>

4 0

3 years ago

Is carbon dioxide a iconic or covalent compound

igomit [66]

It is a covalant bond. Because any compound made up of nonmetals will be covalant. Compounds made up of a non metal and metal willl form a ionic compund. :)

3 0

3 years ago

Two objects are dropped into beaker with layers of oil, rubbing alcohol, water and corn syrup. These objects are made of the sam

Mademuasel [1]

It all depends on the objects' densities ,because if they're less dense than the oil they will not even sink to the bottom of the beaker

6 0

3 years ago

What is causing weathering and erosion of rock?

postnew [5]

Answer:

Physical Weathering

Physical or mechanical weathering is the disintegration of rock into smaller pieces. Physical weathering is often caused by atmospheric changes such as heat or freezing temperatures. Frost wedging results when water freezes and expands in crevices, causing the rock to crack. Also, extreme temperature changes such as rapid heating and cooling can cause the rock to expand and contract. Plants cause weathering when roots growing on or under rocks gradually break the rock apart. In addition, animals such as rodents, earthworms, and insects often disrupt and break rock apart by burrowing and digging. The Wind is another force that causes abrasive weathering by blowing sand against rock faces.

Chemical Weathering

Chemical weathering is the disintegration of rock caused by chemical alteration of the mineral structure. According to Tulane University, the main cause of chemical weathering is the presence of weak acids in water coming in contact with the rock. For example, the reaction of carbon dioxide gas in rainwater can produce carbonic acid that dissolves some minerals, especially limestone. Acid rain caused by pollution such as factory and car exhaust is another agent of chemical weathering. Chemical weathering also occurs when iron in rock oxidizes or rusts. In addition, certain types of lichens and fungi growing on rock secrete acids that etch stone surfaces.

Water Erosion

Heavy rainfall and flooding can wash soil, rock, and sediment away into rivers and streams. Water erosion reshapes shorelines and deposits soil in new locations. Materials can be swept away by the water’s force or dissolved in the water and washed away. In addition, when organic material, which helps retain soil structure, is washed from topsoil, the soil becomes more prone to erosion.

Wind Erosion

The Wind is a powerful erosive force, especially when soil is depleted and dry. Sand and soil are swept up and carried away in clouds of dust. A classic example of soil erosion caused by wind and other factors occurred during the “Dust Bowl Years” of the 1930s. Severe drought and wind, combined with 100 years of poor soil management, led to the devastating erosion of topsoil and formation of giant dust clouds that moved across the prairies of the American Great Plains.

Gravity

Gravity is another force that contributes to erosion, especially when combined with slope. Gravity pulls rocks and boulders down mountainsides and chunks of ice down glaciers. Gravitational pull also helps move water laden with dirt and weathered materials to low-lying areas.

Explanation:

All of these cause weathering and erosion.

7 0

3 years ago