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DerKrebs [107]
3 years ago
13

Z ktorých prvkov sú zložené uhľovodíky.

Chemistry
1 answer:
fredd [130]3 years ago
3 0

Answer: A hydrocarbon is an organic compound composed only of carbon and hydrogen.

Explanation:

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Binary systems account for approximately what proportion of star systems in the universe
irinina [24]
One third; or 33.34%
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4 years ago
Which of the reactions are exothermic?
Nutka1998 [239]

Answer:

Reaction A, B, E and F are exothermic reactions.

Explanation:

Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system.

The total enthalpy of the reaction (\Delta H) comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system.

The total enthalpy of the reaction (\Delta H) comes out to be positive.

So, from the given option reaction which are exothermic are with negative value (\Delta H) that enthalpy of reaction and those are:

1) 2Mg(s) + O_2( g )\rightarrow 2MgO (s),ΔH = -1203 kJ/mol

2)NH_3 (g) + HCl (g)\rightarrow NH_4Cl (s),ΔH =-176 kJ/mol

3) C(graphite) + O_2 (g)\rightarrow CO_2 (g),ΔH = -393.5 kJ/mol

4) CH_4 (g) + 2O2 (g)\rightarrow CO_2 (g) + 2H_2O (l),ΔH =-891 kJ/mol

6 0
4 years ago
If an acid is splashed on your skin, wash at once with
olga55 [171]
D. plenty of water

First, the affected area is washed with plenty of water for 15-20 minutes. Then washed with a weak solution of sodium bicarbonate.

H⁺ + HCO₃⁻ → H₂O + CO₂
6 0
3 years ago
Calorimetry can be used to find heats of combustion. suppose a calorimeter helps someone to determine that 4032 kj of heat is re
bezimeni [28]

Answer:

1008.0 kJ.

Explanation:

  • Firstly, we need to calculate the no. of moles of 88.0 g of propane:

<em>n = mass/molar mass </em>= (88.0 g)(/(44.0 g/mol) = <em>2.0 mol.</em>

∴ The combustion of 2.0 moles of propane produces 4032.0 kJ.

<em><u>Using cross multiplication: </u></em>

The combustion of 2.0 moles of propane produces → 4032.0 kJ.

The combustion of 0.5 moles of propane produces → ??? kJ.

<em>∴ The amount of heat released for the combustion of 0.5 moles of propane </em>= (4032.0 kJ)(0.5 mol)/(2.0 mol) = <em>1008.0 kJ.</em>

8 0
3 years ago
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If a trait varies greatly within a pair of identical twins, it is most likely caused by what?
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Answer:

1. B. environment

2. A. true

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