The energy change when the temperature of 0.750 kg of water decreased from 123 °C to 23.0 °C is -313.5 kJ.
In this problem, we are dealing with specific heat which is referred to as the sum of heat per unit mass required to raise the temperature by one degree Celsius.Since we know the boiling point of water is 100°C, at 123°C, the water is steam.
The formula we are referring to for calculating the heat energy Q
Q= m C ΔT
where m is the mass of water which is equal to 0.750 Kg, then
C is the specific heat of water equal to 4180 J/Kg °C and
ΔT is the change in temperature which is (23-123)= -100°C
So, assembling those desired values on the formula we get,
Q= 0.750 (4180) (-100)
Q=-313500
= -313.5 kJ
To know more about specific heat refer to the link brainly.com/question/13163208?referrer=searchResults.
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Hi there.
Alkali metals are known as the group 1 elements.
When we know this, we just have to look to group 1 of the periodic table.
Rb (Rubidium) is in group 1; it is classified as an alkali metal.
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The percent yield : 81.5%
<h3>Further explanation</h3>
Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated
General formula:
Percent yield = (Actual yield / theoretical yield )x 100%
An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients
Reaction
2CO+O₂⇒2CO₂
mol CO(MW=28,01 g/mol)

mass CO₂ (theoretical)(MW=44,01 g/mol)

the percent yield :

Answer: Compound
Explanation:
Copper(II) oxide or cupric oxide is the inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu₂O or copper(I) oxide. As a mineral, it is known as tenorite.
Explanation:
Chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements. methane moleculeMethane, in which four hydrogen atoms are bound to a single carbon atom, is an example of a basic chemical compound.....
Hope it helps..