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3 years ago

Which reaction is endothermic?

Chemistry

2 answers:

Viefleur [7K]3 years ago

7 0

Answer:

The endothermic reaction is:

$\frac{1}{2}N_2(g) + O_2(g) + 8.1 kcal \rightarrow NO_2(g)$

Explanation:

Endothermic reaction is a type of of chemical reaction in which energy is absorbed from the surrounding. The temperature of the surrounding decreases. Energy absorbed is used during the chemical reaction.

So from the given reactions the endothermic reaction is;

$\frac{1}{2}N_2(g) + O_2(g) + 8.1 kcal \rightarrow NO_2(g)$

In this reaction 8.1 kcal of enrgy is used by the reactants to give product.

Where as chemical reaction in which energy is released during the reaction is termed as exothermic reaction.

Naily [24]3 years ago

3 0

The second equation is endothermic. the energy is listed in the reactants side. if it was a product it is exothermic. also the H value is negative exothermic positive endothermic

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The half-life of a pesticide determines its persistence in the environment. A common pesticide degrades in a first-order process

denis23 [38]

Answer:

0.1066 hours

Explanation:

A common pesticide degrades in a first-order process with a rate constant (k) of 6.5 1/hours. We can calculate its half-life (t1/2), that is, the times that it takes for its concentration to be halved, using the following expression.

t1/2 = ln2/k

t1/2 = ln2/6.5 h⁻¹

t1/2 = 0.1066 h

The half-life of the pesticide is 0.1066 hours.

7 0

3 years ago

Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the following equation: CO2(s)→C

GREYUIT [131]

Answer:

$m=8.79kg$

Explanation:

First of all we need to calculate the heat that the water in the cooler is able to release:

$Q=\rho * V*Cp*\Delta T$

Where:

Cp is the mass heat capacity of water
V is the volume
$\rho$ is the density

$Q=1 g/cm^3 *15000 cm^3*4.184 \frac{J}{g*^{\circ}C}*(10-90)^{\circ}C$

$Q=-5020800 J=-5020.8 kJ$

To calculate the mass of CO2 that sublimes:

$-Q=\Delta H_{sub}*m$

Knowing that the enthalpy of sublimation for the CO2 is: $\Delta H_{sub}=571 kJ/kg$

$5020.8 kJ=571 kJ/kg*m$

$m=\frac{5020.8 kJ}{571 kJ/kg}=8.79kg$

6 0

3 years ago

Read the given equation. 2Na + 2H2O ? 2NaOH + H2 During a laboratory experiment, a certain quantity of sodium metal reacted with

emmasim [6.3K]

Answer:

The number of moles of Na metal that used initially = 0.70 mol.

The quantity of Na metal used initially to produce 7.80 of H₂ gas = 16.02 g.

Explanation:

It is a stichiometry problem.

2Na + 2H₂O → 2NaOH + H₂,

The balanced equation shows that 2.0 moles of Na metal react with 2.0 moles of water to produce 2.0 moles of NaOH and 1.0 mole of H₂,

Firstly, we need to convert the volume of H₂ (7.80 L) produced to no. of moles (n) using the ideal gas law: PV = nRT,

where, P is the pressure of the gas in atm (P at STP = 1.0 atm),

V is the volume of the gas in L (V = 7.80 L),

n is the number of moles in mole,

R is the general gas constant (R = 0.082 L.atm/mol),

T is the temperature of the gas in K (T at STP = 0.0 °C + 273 = 273.0 K).

∴ The number of moles of H₂ gas (n) = PV / RT = [(1.0 atm)(7.80 L)] / [(0.082 L.atm/mol.K)(273.0 K)] = 0.35 mol.

Using cross multiplication:

2.0 moles of Na will produce → 1.0 mole of H₂, from the stichiometrey.

??? moles of Na will produce → 0.35 mole of H₂.

∴ The number of moles of Na metal that used initially = (2.0 mol)(0.35 mol) / (1.0 mol) = 0.70 mol.

Now, we can get the quantity of Na metal using the relation:

∴ mass = n x molar mass = (0.70 mol)(22.989 g/mol) = 16.02 g.

6 0

3 years ago

when the following redoc reaction is balances (assume acidic solution), how many moles of water appear and on what side

PolarNik [594]

8 moles of water on the right side.

An oxidation-reduction or redox reaction is a reaction that involves the transfer of electrons between chemical items (the atoms, ions, or molecules involved in the reaction).

Redox reactions: the burning of fuels, the corrosion of metals, and even the processes of photosynthesis and cellular respiration involve oxidation and reduction.

Step 1:

MnO4- ----> Mn2+

2Cl- ------> Cl2

Step 2:

MnO4- --> Mn2+ + 4H2O

2Cl- -----> Cl2

Step 3:

8H+ + MnO4- ------> Mn2+ + 4H2O

2Cl- ----->Cl2

Step 4:

8H+ + MnO4- +5e- ------>Mn2+ + 4H2O

2Cl- ----> Cl2+ 2e-

Step 5:

16 H+ +2 MnO4- +10Cl- ----->2 Mn2+ + 8H2O+5Cl2

This is the balanced equation in an acidic medium.

That is 8, right side.

To know more about redox reaction follow the link:

https://brainly.in/question/9854479

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1 year ago

Thallium consists of 29.5%TI-203 and 70.5%TI-205. What is the relative atomic mass of thallium

Galina-37 [17]

To determine the relative atomic mass of thallium, we multiply the molar mass of the isotopes to their corresponding relative abundance. The molecular percentages should sum up to 1. In this case, we multiply 203 by 0.295 and 205 by 0.705 and add the answers of the two. The final atomic mass is 204.41 g/mol.

3 0

3 years ago