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2 years ago

(copied from last question and fixed) (there's three question so triple points)

Chemistry

1 answer:

hammer [34]2 years ago

7 0

Question 1: A

Question 2: B

Question 3: B

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What reagent is used to test for the presence of indole?

lubasha [3.4K]

The indole test is a qualitative procedure for determining the ability of bacteria to produce indole by deamination of tryptophan. Using Kovacs tube method, indole combines, in the presence of a tryptophan rich medium, with p-Dimethylaminobenzaldehyde at an acid pH in alcohol to produce a red-violet compound.

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2 years ago

A plant living in the environment shown in the picture would have to be adapted not to loose to much water through its___

Ray Of Light [21]

Answer:

Many plants have thorns on their stems or leaves. What is the MOST likely explanation for the evolution of thorns?

A) Thorns help plants produce more food from photosynthesis.

B) Thorns are an example of a mutation that arises in the genetic code of plants.

C) Thorns help plants to conserve resources like water and soil nutrients that may be used by other organisms.

D) Thorns are an adaptation that some plants have evolved in order to discourage herbivores from eating the plant.

Explanation:

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2 years ago

Read 2 more answers

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

rite stepwise equations for protonation or deprotonation of this polyprotic species in water. What are the products of the first

adoni [48]

Answer: The products of the given chemical equation are $HCO_3^-\text{ and }OH^-$

Explanation:

Protonation equation is defined as the equation in which protons get added in the substance.

The chemical equation for the protonation of carbonate ion in the presence of water follows:

$CO_3^{2-}+H_2O\rightarrow HCO_3^-+OH^-$

By Stoichiometry of the reaction:

1 mole of carbonate ion reacts with 1 mole of water to produce 1 mole of hydrogen carbonate ion and 1 mole of hydroxide ion

Hence, the products of the given chemical equation are $HCO_3^-\text{ and }OH^-$

3 0

3 years ago

How many grams of Ni are formed from 55.3 g of Ni2O3? 2Ni2O3(s)⟶4Ni(s)+3O2(g)

Neko [114]

Answer:

39.2 g

Explanation:

2Ni₂O₃(s) ⟶ 4Ni(s) + 3O₂(g)

First we convert 55.3 grams of Ni₂O₃ into moles of Ni₂O₃, using its molar mass:

55.3 g ÷ 165.39 g/mol = 0.334 mol Ni₂O₃

Then we convert 0.334 moles of Ni₂O₃ into moles of Ni, using the stoichiometric coefficients of the balanced reaction:

0.334 mol Ni₂O₃ * $\frac{4molNi}{2molNi_2O_3}$ = 0.668 mol Ni

Finally we calculate how much do 0.668 Ni moles weigh, using the molar mass of Ni :

0.668 mol Ni * 58.69 g/mol = 39.2 g

7 0

2 years ago