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3 years ago

Classify each reaction as endothermic or exothermic.

Chemistry

2 answers:

evablogger [386]3 years ago

7 0

H2 + Br2 → 2HBr, ΔH = -73 kJ Exothermic

2NH3 → N2 + 3H2, ΔH = 92 kJ Endothermic

CH4 + 2O2 → CO2 + 2H2O, ΔH = -890 kJ Exothermic

2HCl → H2 + Cl2, ΔH = 184 kJ Endothermic

Alik [6]3 years ago

5 0

The correct answers are

Exothermic:

H2 + Br2 → 2HBr, ΔH = -73 kJ

CH4 + 2O2 → CO2 + 2H2O, ΔH = -890 kJ

Endothermic

2NH3 → N2 + 3H2, ΔH = 92 kJ

2HCl → H2 + Cl2, ΔH = 184 kJ

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I just started learning about kinetic molecular theory, and I’m not sure how to answer the question circled below

lions [1.4K]

Answer : The value of 'R' is $0.0821\text{ L atm }mol^{-1}K^{-1}$

Solution : Given,

At STP conditions,

Pressure = 1 atm

Temperature = 273 K

Number of moles = 1 mole

Volume = 22.4 L

Formula used : $R=\frac{PV}{nT}$

where,

R = Gas constant

P = pressure of gas

T = temperature of gas

V = volume of gas

n = number of moles of gas

Now put all the given values in this formula, we get the values of 'R'.

$R=\frac{(1atm)\times (22.4L)}{(1mole)\times (273K)}$

$R=0.0821\text{ L atm }mol^{-1}K^{-1}$

Therefore, the value of 'R' is $0.0821\text{ L atm }mol^{-1}K^{-1}$ .

7 0

3 years ago

Which statement is true regarding the diagram of circle P? The sum of y and z must be 2x. The sum of y and z must be x. The diff

olga2289 [7]

Answer:

The difference of Z and Y must be 2x

Explanation:

6 0

3 years ago

Read 2 more answers

qual a concentração de uma solução contendo 50g de cloreto de sódio dissolvidos em 250ml de solução

anygoal [31]

Answer:

200 g/L

Explanation:

The concentration of a solution (also called molarity) can be calculated with the formula:

$M=\frac{m}{V}$

where

m is the mass of the solute

V is the volume of the solution

For the solution in this problem we have:

m = 50g is the mass of the solute

V = 250 mL = 0.250 L is the volume of the solution

Therefore, the concentration of the solution is:

$M=\frac{50 g}{0.250 L}=200 g/L$

6 0

3 years ago

The compound known as diethyl ether, commonly referred to as ether, contains carbon, hydrogen, and oxygen. A 1.751 g sample of e

fredd [130]

Answer: The empirical formula for the given compound is $C_{4}H_{10}O$

Explanation:

The chemical equation for the combustion of ether follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=4.159g$

Mass of $H_2O=2.128g$

Mass of sample = 1.751 g

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 4.159 g of carbon dioxide, $\frac{12}{44}\times 4.159=1.134g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 2.128 g of water, $\frac{2}{18}\times 2.128=0.236g$ of hydrogen will be contained.

Mass of oxygen in the compound = (1.751) - (1.134 + 0.236) = 0.381 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{1.134g}{12g/mole}=0.0945moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.236g}{1g/mole}=0.236moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{0.381g}{16g/mole}=0.0238moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.0238 moles.

For Carbon = $\frac{0.0945}{0.0238}=3.97\approx 4$

For Hydrogen = $\frac{0.236}{0.0238}=9.91\approx 10$

For Oxygen = $\frac{0.0238}{0.0238}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 4 : 10 : 1

Hence, the empirical formula for the given compound is $C_{4}H_{10}O$

7 0

3 years ago

Jason is preparing curry from an Indian cookbook his British brother-in-law gee him for his birthday. Unfortunately, the British

Marina CMI [18]

Answer:

0.99 pounds

2,000 oz

0.423 cups

Explanation:

In order to convert this units we need to look up their equivalences.

1 g equals 0,0022 pounds approximately

Then we need to cross-multiply:

$\frac{1 g}{0.0022 pounds} = \frac{450 g}{ Xpounds} \\x = \frac{450 g x 0.0022 pounds}{1 g}$

450 g equals 0.99 pounds approximately

We can do the same calculation for the other 2 ingredients

1 g equals 16 oz

Then (125 g x 16 oz) / 1 oz = 2,000 oz (or 500 4 oz)

1 cup equals 236.59 ml

Then (100 ml x 1 cup)/ 236.59 = 0.423 cups

6 0

3 years ago