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3 years ago

Based on Reference Table I, which change occurs when pellets of solid NaOH are added to water and stirred?

2 answers:

8 0

The correct answer is option 1. When pellets of solid NaOH are added to water and stirred, the temperature of water increases because chemical energy is converted into heat energy. Dissolution of sodium hydroxide in water is an exothermic process where heat is dissipated.

kicyunya [14]3 years ago

3 0

The correct answer is option 1, that is, the temperature of the water increases as chemical energy gets transformed into heat energy.

When the pellets of sodium hydroxide are mixed and stirred in water, the dilution of sodium hydroxide takes place, and then it gets dissociated into ions, the whole process is exothermic. The dissolution of sodium hydroxide is tremendously exothermic, the chemical burns as well as thermal burns can take place.

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At construction sites, workers often reduce erosion by ____.

Naddik [55]

<h3>Answer;</h3>

All the above

Workers at construction sites often reduce erosion by;

Moving excess sediment back to its original location
Planting trees
Spraying water on bare soil

<h3>Explanation;</h3>

Soil erosion is a naturally occurring process which involves the wearing away of the topsoil by natural forces such as wind, water or other forces associated with farming.
Construction of roads and buildings results to large amounts of soil erosion around the world. It is therefore important to put measures that would help reduce soil erosion at construction sites. These measures uses principals of soil control such as implementing sediment control, limiting soil exposure, reducing the runoff velocity, and modifying topography among others.

5 0

3 years ago

A gaseous mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H20. What is the average molecular weight of the mixture? a

Semenov [28]

Answer: The correct answer is Option d.

Explanation:

We are given:

Mass percentage of $CH_4$ = 20 %

So, mole fraction of $CH_4$ = 0.2

Mass percentage of $C_2H_4$ = 30 %

So, mole fraction of $C_2H_4$ = 0.3

Mass percentage of $C_2H_2$ = 35 %

So, mole fraction of $C_2H_2$ = 0.35

Mass percentage of $C_2H_2O$ = 15 %

So, mole fraction of $C_2H_2O$ = 0.15

We know that:

Molar mass of $CH_4$ = 16 g/mol

Molar mass of $C_2H_4$ = 28 g/mol

Molar mass of $C_2H_2$ = 26 g/mol

Molar mass of $C_2H_2O$ = 48 g/mol

To calculate the average molecular mass of the mixture, we use the equation:

$\text{Average molecular weight of mixture}=\frac{_{i=1}^n\sum{\chi_im_i}}{n_i}$

where,

$\chi_i$ = mole fractions of i-th species

$m_i$ = molar masses of i-th species

$n_i$ = number of observations

Putting values in above equation:

$\text{Average molecular weight}=\frac{(\chi_{CH_4}\times M_{CH_4})+(\chi_{C_2H_4}\times M_{C_2H_4})+(\chi_{C_2H_2}\times M_{C_2H_2})+(\chi_{C_2H_2O}\times M_{C_2H_2O})}{4}$

$\text{Average molecular weight of mixture}=\frac{(0.20\times 16)+(0.30\times 28)+(0.35\times 26)+(0.15\times 42)}{4}\\\\\text{Average molecular weight of mixture}=6.75$

Hence, the correct answer is Option d.

3 0

3 years ago

What is responsible for the larger size of an anion in comparison with the atom from which it is form?

GarryVolchara [31]

Answer:

electron-electron repulsion

Explanation:

When electrons add into valence shell of neutral elements, the element assumes a negative oxidation state. With this, the number of electrons having (-) charges will be larger than the number of protons having positive (+) charges. As a result, the extra electrons repel one another (i.e., like charges repel) and a larger radius is the result.

In contrast, when cations are formed, electrons are removed from the valence level (oxidation) producing an element having a greater number of protons than electrons. The larger number of protons will function to attract the electron cloud with a greater force that results in a contraction of atomic radius and a smaller spherical volume than the neutral unionized element.

To visualize, see attached chart that shows atomic and ionic radii before and after ionization of the elements.

Download pdf

4 0

3 years ago

Polonium has a mass number of 212 and an atomic number of 84. In a balanced nuclear reaction, polonium releases an alpha particl

antoniya [11.8K]

Answer:

D. 82

Explanation:

3 0

2 years ago

Which of the following steps correctly converts 3 moles of fluorine to an equivalent number of particles of fluorine? Divide Avo

Eva8 [605]

Answer:

Multiply 3 by Avogadro's number.

Explanation:

The mole can be defined as the amount of a substance that contains Avogadro’s number of particles, 6.02 x 10²³.

For elementary particles:

Number of particles=

number of moles x 6.02 x10²³

From the question,

Number of moles = 3moles

Number of particles = 3 x 6.02 x10²³

8 0

3 years ago