1550J
Explanation:
Given parameters:
Heat of fusion = 155J/g
Mass of sample = 10g
Unknown:
Quantity of heat removed to freeze the substance =?
Solution:
This is a phase change problem and we apply the formula for the specific heat of fusion to solve the problem:
Q = mL
m is the mass of the substance
L is the specific heat of fusion of the substance.
We then plug the parameters into the equation:
Q = 155J/g x 10g = 1550J
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Each chemical reaction, you may say that there are many possible balanced reactions since the coefficients of the reactants and of the products can be another set of numbers as long as the ratios of the compounds would be the same. The most preferred balanced reaction would be the reaction which have the lowest value of coefficients. Example would be the reaction of HCl and NaOH.
HCl + NaOH = NaCl + H2O (This would be the most preferred one since the coefficients are in the lowest value)
Other equivalents would be:
2HCl + 2NaOH = 2NaCl + 2H2O
3HCl + 3NaOH = 3NaCl + 3H2O
4HCl + 4NaOH = 4NaCl + 4H2O
The energy required to raise the temperature of 3 kg of iron from 20° C to 25°C is 6,750 J( Option B)
<u>Explanation:</u>
Given:
Specific Heat capacity of Iron= 0.450 J/ g °C
To Find:
Required Energy to raise the Temperature
Formula:
Amount of energy required is given by the formula,
Q = mC (ΔT)
Solution:
M = mass of the iron in g
So 3 kg = 3000 g
C = specific heat of iron = 0.450 J/ g °C [ from the given table]
ΔT = change in temperature = 25° C - 20°C = 5°C
Plugin the values, we will get,
Q = 3000 g × 0.450 J/ g °C × 5°C
= 6,750 J
So the energy required is 6,750 J.
It is important to establish the true weight of the crucible because it is a necessary reference point. Later, you will be weighing the crucible to determine how much of the products are present, so it's necessary to have the true tare weight of the crucible.
<span>The crucible is heated to be sure it is free of any moisture or other volatiles that might otherwise give a misleading weight. If you start out with the crucible absolutely clean and dry, (after heating) then you know that any additional weight must have come from the sample.</span>
Answer:
Explanation:
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
Explanation:
This law was given by french chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
Chemical equation:
Mg + HCl → H₂ + MgCl₂
24 g + 36.5 g = 2 g+ 95 g
60.5 g = 97 g
The reaction does not hold the law of conservation of mass, because it is not balanced.
Balanced chemical equation:
Mg + 2HCl → H₂ + MgCl₂
24 g + 73 g = 2 g+ 95 g
97 g = 97 g
this equation completely follow the law of conservation of mass.