What is the first element of the periodic table?
Answers
Answer: Hydrogen
I hope this helps;)
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35 kL (1000 liters/ 1 kL) (1 x 10^6 mL/ 1 L) = 3.5 x 10^9 microliters
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Answer:
The factor by which the average kinetic energy of the oxygen molecules in the cylinder decreases is '0.5'.
Explanation:
Average kinetic energy is defined as the average of the kinetic energies of all the particles present in a system. It is determined by the equation:
where,
K = Average kinetic energy
R = Gas constant
T = Temperature of the system
= Avogadro's number
Average kinetic energy of oxygen gas molecule at 300 K.
..[1]
Average kinetic energy of oxygen gas molecule at 150 K.
..[2]
[1] ÷ [2]
The factor by which the average kinetic energy of the oxygen molecules in the cylinder decreases is '0.5'.
Answers
Answer:
0.22 grams of magnesium
This seems too low, so check the calculations/
Explanation:
How is the heat delivered? Is the magnesium hot and added to the water? If so, at what temperature.
Is the heat generated from an exothermic chemical reaction?
=================
I'll assume here that the heat comes from the reaction of magnesium with water. The balanced equation is:
Mg + 2H2O = Mg(OH)2 + H2
It has a heat of reaction of −924.7 kJ/mol.
We need enough Mg to heat 30 ml of water from 22°C to 90°C. The specific heat of water is needed. It is 4.184 J/g-K. It tells us that 4.184 Joules are needed to raise the temperature of water by 1 degree K.
30 ml of water with density 1 gram/ml means we have 30 grams of water. (We'll ignore the water that is added from the chemical reaction.).
Lets calculate the Joules required to raise 30 grams of water from 22°C to 90°C. Note that the specific heat has units of g and Kelvin. Since we need a temperature change, the number value for ΔT is the same for both °C and °K. So the temperature change is +68°K.
We can now calculate the Joules required:
(30 grams H2O)*(4.184 J/g-K)*(+68°K) = 8535.4 Joules or 8.5 kJ to 2 sig figs.
The Mg/H2O heat of reaction of −924.7 kJ/mol. will allow us to calculate the amount of Mg needed to supply 8.5 kJ. The minus sign tells us that the reaction RELEASES energy (the energy leaves the "system" of Mg and H2O).
Calculate the moles of Mg needed to release 8.5 kJ:
(924.7 kJ/mole)*(x moles) = 8.5 kJ
x moles = 0.0092 moles
Whoa. That is only (0.0092 moles)*(24.03 g/mole) = 0.22 grams of magnesium
This seems low to me, so check on the heat of reaction figure I used. And don't let the hydrogen get away.
Answers
Answer: Option (4) is the correct answer.
Explanation:
Activation energy is the minimum amount of energy required by reactant molecules to undergo a chemical reaction.
Whereas a catalyst is defined as the substance that helps in increasing the rate of reaction by decreasing the activation energy without itself getting consumed in the reaction.
When a catalyst decreases the activation energy then molecules with lesser energy become able to participate in the reaction and thus, products are obtained at a faster rate. Hence, a catalyst increases the rate of a reaction.
Thus, we can conclude that a catalyst works by decreasing the activation energy required for a reaction.
(3) The volume of each atom decreases.
(4) The frequency of collisions between atoms increases.
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Answer is: (4) The frequency of collisions between atoms increases.
The average kinetic energy of molecules depends on the temperature.
As temperature increases, molecules gain more energy from surrounding and move faster and have more collisions.
Kinetic energy (standard unit is the joule J) depends on speed of the molecule.
Charles' Law (The Temperature-Volume Law) - the volume of a given amount of gas held at constant pressure is directly proportional to the Kelvin temperature:
V₁/T₁ = V₂/T₂.
When temperature goes up, the volume also goes up.
Hope this helps~
Answers
The combustion reaction of the unknown compound can be written as follows:
Other part of the question is discussed below:
We know that 3.50 g of the compound produced 5.13 g of carbon dioxide and 2.10 g of water. This means that 1.63 g of oxygen were also produced in the reaction.
The mass of oxygen in the original sample is equal to the mass of oxygen produced in the reaction, so the original sample contained 1.63 g of oxygen.
The total mass of carbon and hydrogen in the original sample is equal to the mass of the sample minus the mass of oxygen, which is 3.50 g - 1.63 g = 1.87 g.
We can find the number of moles of hydrogen in the original sample by dividing the mass of hydrogen by the molar mass of hydrogen (1.008 g/mol). This gives us 1.87 g / 1.008 g/mol = 1.86 moles of hydrogen.
Therefore, the answer is 1.86
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Final answer:
By dividing the mass of water produced in combustion by the molar mass of Hydrogen in water, we find that the original compound contained 1.05 mol of Hydrogen.
Explanation:
To determine the mole amount of Hydrogen in the compound, you have to consider the reaction applied, and how it applies to the law of conservation of mass. Combustion of the compound produces carbon dioxide (CO2) and water (H2O). For water, one mol equals to the molar mass of H which is 1 g/mol, times the amount of H in water which is 2 to get 2 g/mol. Now knowing that 2.10 g of water were produced from combustion, we divide this by the molar mass of H-in-water to get the number of hydrogen moles in the original sample. So, the calculation will be 2.10 g/ 2 (g/mol) = 1.05 mol. So, the original compound contained 1.05 mol of hydrogen.
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