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3 years ago

Which of the following statements is true about the periodic table.

Chemistry

2 answers:

mixer [17]3 years ago

8 0

Answer:

In this question, the statement 2 is correct and true while other statements are incorrect.

Explanation:

The properties of an element can be easily predicted from the periodic table. We can find out the atomic number of the element from the periodic table. According to the periodic table, the properties of element is dependent on the atomic number of the element. The behavior of element during a chemical reaction can be predicted from the atomic number.

Element can only belong to one group at a time. Hence, statement (3) is not correct.

The periodic table is still used by scientists for predicting the properties. Hence, it is not outdated. Statement (1) is not correct.

Statement (2) is correct

kodGreya [7K]3 years ago

5 0

Answer: 2

Explanation:

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What is the lewis structure for HCL + Na?

saul85 [17]

Answer:

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3 0

3 years ago

Ethanol (C2H5OH) melts a - 144 oC and boils at 78 °C. The enthalpy of fusion of ethanol is 5.02 kj/mol, and its enthalpy of vapo

hammer [34]

Answer:

For a: The total heat required is 36621.5 J

For b: The total heat required is 58944.5 J

Explanation:

For a:

To calculate the heat required at different temperature, we use the equation:

$q=mc\Delta T$ .........(1)

where,

q = heat absorbed

m = mass of substance

$c$ = specific heat capacity of substance

$\Delta T$ = change in temperature

To calculate the amount of heat required at same temperature, we use the equation:

$q=m\times \Delta H$ ........(2)

where,

q = heat absorbed

m = mass of substance

$\Delta H$ = enthalpy of the reaction

The processes involved in the given problem are:

$1.)C_2H_5OH(l)(35^oC)\rightarrow C_2H_5OH(l)(78^oC)\\2.)C_2H_5OH(l)(78^oC)\rightarrow C_2H_5OH(g)(78^oC)$

For process 1:

We are given:

Change in temperature remains the same.

$m=42.0g\\c_l=2.3J/g.K\\T_2=78^oC\\T_1=35^oC\\\Delta T=[T_2-T_1]=[78-35]^oC=43^oC=43K$

Putting values in equation 1, we get:

$q_1=42.0g\times 2.3J/g.K\times 43K\\\\q_1=4153.8J$

For process 2:

We are given:

Conversion factor: 1 kJ = 1000 J

Molar mass of ethanol = 46 g/mol

$m=42.0g\\\Delta H_{vap}=38.56kJ/mol=\frac{35.56kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=773.04J/g$

Putting values in equation 2, we get:

$q_2=42.0g\times 773.04J/g\\\\q_2=32467.7J$

Total heat required = $[q_1+q_2]$

Total heat required = $[4153.8J+32467.7J]=36621.5J$

Hence, the total heat required is 36621.5 J

For b:

The processes involved in the given problem are:

$1.)C_2H_5OH(s)(-155^oC)\rightarrow C_2H_5OH(s)(-144^oC)\\2.)C_2H_5OH(s)(-144^oC)\rightarrow C_2H_5OH(l)(-144^oC)\\3.)C_2H_5OH(l)(-144^oC)\rightarrow C_2H_5OH(l)(78^oC)\\4.)C_2H_5OH(l)(78^oC)\rightarrow C_2H_5OH(g)(78^oC)$

For process 1:

We are given:

Change in temperature remains the same.

$m=42.0g\\c_s=0.97J/g.K\\T_2=-144^oC\\T_1=-155^oC\\\Delta T=[T_2-T_1]=[-144-(-155)]^oC=11^oC=11K$

Putting values in equation 1, we get:

$q_1=42.0g\times 0.97J/g.K\times 11K\\\\q_1=448.14J$

For process 2:

We are given:

$m=42.0g\\\Delta H_{fusion}=5.02kJ/mol=\frac{5.02kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=109.13J/g$

Putting values in equation 2, we get:

$q_2=42.0g\times 109.13J/g\\\\q_2=4583.5J$

For process 3:

We are given:

Change in temperature remains the same.

$m=42.0g\\c_l=2.3J/g.K\\T_2=78^oC\\T_1=-144^oC\\\Delta T=[T_2-T_1]=[78-(-144)]^oC=222^oC=222K$

Putting values in equation 1, we get:

$q_3=42.0g\times 2.3J/g.K\times 222K\\\\q_3=21445.2J$

For process 4:

We are given:

$m=42.0g\\\Delta H_{vap}=38.56kJ/mol=\frac{38.56kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=773.04J/g$

Putting values in equation 2, we get:

$q_4=42.0g\times 773.04J/g\\\\q_4=32467.7J$

Total heat required = $[q_1+q_2+q_3+q_4]$

Total heat required = $[448.14+4583.5+21445.2+32467.7]J=58944.5J$

Hence, the total heat required is 58944.5 J

8 0

3 years ago

N2O5 decomposes to form NO2 and O2 with first-order kinetics. The initial concentration of N2O5 is 3.0 M and the reaction runs f

kow [346]

Answer : The final concentration of $N_2O_5$ is, 2.9 M

Explanation :

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $5.89\times 10^{-3}\text{ min}^{-1}$

t = time passed by the sample = 3.5 min

a = initial concentration of the reactant = 3.0 M

a - x = concentration left after decay process = ?

Now put all the given values in above equation, we get

$3.5=\frac{2.303}{5.89\times 10^{-3}}\log\frac{3.0}{a-x}$

$a-x=2.9M$

Thus, the final concentration of $N_2O_5$ is, 2.9 M

3 0

3 years ago

Drag each characteristic to the correct category.

andrew11 [14]

Answer/Explanation

Characteristics of Life Present in Viruses:

has a defined boundary - viruses are made up simply of genetic material surrounded by a protein capsid and sometimes a lipid membrane

Characteristics of Life Absent in Viruses:

made up of one or more cells - one of the main arguments for why viruses are not living is that they are not cellular
uses energy - this is a tricky one. They don't use or produce their own energy. However, in order to reproduce they do hijack the host cells and steal energy from them in order to reproduce
exhibits growth and development - although viruses do reproduce, the individual viral particles do not exhibit growth or development
possess internal organisation - other than the fact they ahve genetic material, the inside of a virus does not contain internal organization like a cytosol, instead conssiting of the bare minimum amount of proteins to survive
eliminates waste - since they do not have their own metabolism, they have no waste to eliminate

4 0

3 years ago

Consider the chemical equation in equilibrium. A(g) 2B(g) Double headed arrow. C(g) D(g) heat What will happen to the equilibriu

Mazyrski [523]

If the temperature is increased then reaction will shift to the left because heat is absorbed.

<h3>What is equilibrium state?</h3>

Equilibrium of any reaction is that state in which concentration of reactant and concentration of product will be constant.

Given chemical reaction is:

A(g) + 2B(g) ⇄ C(g) + D(g)

From the equilibrium state reaction will move only that side which will contribute to maintain the stable state. In the forward reaction heat is released as mention in the question. So, when the temperature of reaction is increased then it shifts towards the left side by absorbing the heat and maintain the stability.

Hence, option (2) is correct, i.e. It will shift to the left because heat is absorbed.

To know more about equilibrium, visit the below link:

brainly.com/question/14297698

6 0

2 years ago