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likoan [24]
3 years ago
12

Which of these statements is not true about chemical reaction rates? a Temperature can change a reaction rate. b The amount of r

eactants can increase the reaction rate. c Temperature can decrease the reaction rate. d Temperature does not affect the reaction rate.
Chemistry
1 answer:
Umnica [9.8K]3 years ago
4 0

Answer:

The statement that is not true is: 'Temperature does not affect the reaction rate'.  

Explanation:

a) Temperature can change a reaction rate. <u> This is true</u>

Increasing the temperature increases the reaction rates because of the disproportionately large increase in the number of high energy collisions. It is only these collisions (possessing at least the activation energy for the reaction) which result in a reaction.

For example, the time taken to melt a metal will be much higher at a lower temperature but it will decrease as soon as we increase the temperature

b) The amount of reactants can increase the reaction rate.<u> This is true</u>

A higher concentration of reactants leads to more effective collisions per unit time, which leads to an increased reaction rate.

c) Temperature can decrease the reaction rate. <u>This is true </u>

Decreasing the temperature decreases the reaction rates because of the  decrease in the number of high energy collisions. It will result in a slower reaction.

d) Temperature does not affect the reaction rate.  <u>This is not true. </u>

The reaction rate is temperature dependent. The reaction rate increases with higher temperature and decreases with lower temperature.

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A gaseous compound is 30.4 % N and 69.6% OF. A 5.25 g sample of the gas occupies a volume of 1.00 L and exerts a pressure of 958
Harman [31]

Answer:

The molecular formula = N2O4

Explanation:

<u>Step 1</u>: Data given

A gaseous compound is 30.4 % N and 69.6%

Mass of the compound = 5.25 grams

Volume of the gas = 1.00 L

Pressure of the gas = 958 mmHg = 1.26 atm

Temperature of the gas = -4 °C = 273 -4°C = 269 Kelvin

Molar mass of N = 14 g/mol

Molar mass of O = 16 g/mol

<u>Step 2</u>: Calculate mass of N

Mass of Nitrogen = 5.25 grams * 0.304 = 1.596 grams

<u>Step 3:</u> Calculate mass of O

Mass of Oxygen = 5.25 grams * 0.696 = 3.654 grams

<u>Step 4:</u> Calculate number of moles N

Number of moles N = Mass of N/ Molar mass of N

Moles of N = 1.596 grams / 14g/mol

Moles of N = 0.114 moles N

<u>Step 5:</u> Calculate moles of O

Moles O = 3.654 grams / 16 g/mol

Moles 0 = 0.2884 moles

<u>Step 6:</u> Calculate empirical formule

We calculate the empirical formule by dividing number of moles by the smallest number of mol

N : 0.114 / 0.114 = 1

O: 0.2284 / 0.114 = 2

Empirical formule = NO2

<u>Step 7: </u>Calculate number of moles of 5.25 g sample via gas law:

p*V = nRT

⇒ with p = the pressure = 1.26 atm

⇒ with v = 1.00 L

⇒ with n = the number of moles = TO BE DETERMINED

⇒ with R = the gas constant = 0.08206 L*atm/ K*mol

⇒ with T = the temperature = 269 K

number of moles n = (p*V)/(R*T)

n = (1.26*1L)/(0.08206*269)

n = 0.057 mol  

<u>Step 8:</u> Calculate molar mass of the compound

This means 5.25 grams of the gas = 0.057 moles

So 1 mol of the compound has a molar mass of: 5.25 / 0.057 = 92.11 g/mol

<u>Step 9</u>: Calculate molar mass of the empirical formula NO2

N = 14 g/mol

O = 16 g/mol

NO2 = 14 + 16 + 16 = 46 g/mol

The empirical formule NO2 has a molar mass of 46 g/mol

<u>Step 10</u>: Calculate molecular formula

92.11 / 46 = 2

This means the empirical formula should be multiplied by 2

2*(NO2) = N2O4

The molecular formula = N2O4

8 0
2 years ago
Write a net ionic equation for the reaction that occurs when excess hydrochloric acid (aq) and potassium sulfite (aq) are combin
Ket [755]

<u>Answer:</u> The net ionic equation for the given reaction is 2H^+(aq.)+SO_3^{2-}(aq.)\rightarrow H_2O(l)+SO_2(g)

<u>Explanation:</u>

Net ionic equation of any reaction does not include any spectator ions.

Spectator ions are the ions which do not get involved in a chemical equation. It is also defined as the ions that are found on both the sides of the chemical reaction when it is present in ionic form.

The chemical equation for the reaction of hydrochloric acid and potassium sulfite is given as:

2HCl(aq.)+K_2SO_3(aq.)\rightarrow 2KCl(aq.)+SO_2(g)+H_2O(l)

Ionic form of the above equation follows:

2H^+(aq.)+2Cl^-(aq.)+2K^+(aq.)+SO_3^{2-}(aq.)\rightarrow 2K^+(aq.)+2Cl^-(aq.)+SO_2(g)+H_2O(l)

As, potassium and chloride ions are present on both the sides of the reaction, thus, it will not be present in the net ionic equation.

The net ionic equation for the above reaction follows:

2H^+(aq.)+SO_3^{2-}(aq.)\rightarrow SO_2(g)+H_2O(l)

Hence, the net ionic equation for the given reaction is written above.

7 0
3 years ago
It is found that doubling the concentration of a quadruples the reaction rate and tripling the concentration of b triples the re
MatroZZZ [7]
Reactant A must be second order and reactant B first order. Overall = add them so 3rd order.
4 0
3 years ago
Problem page in each of the molecules drawn below one chemical bond is colored red. decide whether this bond is likely to be pol
Slav-nsk [51]

The question is incomplete, here is the complete question:

Problem page in each of the molecules drawn below one chemical bond is colored red. Decide whether this bond is likely to be polar or not. if the bond is likely to be polar, write down the chemical symbol for the atom which will have more negative charge.

The image is attached below.

<u>Answer:</u>

<u>For carbon dioxide molecule:</u> The bond is considered as polar and the elecvtronegative atom is oxygen.

<u>For water molecule:</u> The bond is considered as polar and the elecvtronegative atom is oxygen.

<u>Explanation:</u>

There are two types of covalent bonds:

  • <u>Polar covalent bond:</u> This bond is formed when difference in electronegativity between the atoms is present. When atoms of different elements combine, it results in the formation of polar covalent bond. <u>For Example:</u> CO_2,NO_2 etc..
  • <u>Non-polar covalent bond:</u> This bond is formed when there is no difference in electronegativity between the atoms. When atoms of the same element combine, it results in the formation of non-polar covalent bond. <u>For Example:</u> N_2,O_2 etc..

<u>In carbon dioxide molecule:</u>

The given bond is present between C and O atom.

Electronegativity value of C = 2.5

Electronegativity value of O = 3.5

Electronegativity difference = (3.5 - 2.5) = 1

As, electronegativity difference is present. So, the bond is considered as polar and the elecvtronegative atom is oxygen.

<u>In water molecule:</u>

The given bond is present between H and O atom.

Electronegativity value of H = 2.1

Electronegativity value of O = 3.5

Electronegativity difference = (3.5 - 2.1) = 1.4

As, electronegativity difference is present. So, the bond is considered as polar and the elecvtronegative atom is oxygen.

8 0
3 years ago
The name for Na2 O in chemistry ​
IgorC [24]
Pretty sure it’s sodium oxide.. ?
5 0
3 years ago
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