ANSWER
EXPLANATION
Given that
The energy released by the system is 12.4J
Work done on the surrounding is 4.2J
Follow the steps below to find the change in energy
In the given data, energy is said to be released to the surroundings
Recall, that exothermic reaction is a type of reaction in which heat is released to the surroundings. Hence, change in enthalpy is negative
Step 1; Write the formula for calculating change in energy
Since heat is released to the surrounding, then q = -12J
Recall, that work done by the system on the surroundings is always negative
Hence, w = -4.2J
Step 2; Substitute the given data into the formula in step 1
Therefore, the change i
<span>Melting, freezing, and boiling are "Phase" Changes
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Yes diatoms are protist as algae they have an inorganic cell wall that is made of silicon dioxide or hydrated silica
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Answer: The greenhouse gases cause Earth's surface to heat up from the sunlight.
Explanation: The greenhouse gases causes the Earth's surface to warm up in the morning and at night, the surface cools down. When it cools down, that gives the heat a chance to get back into the air, but some of the heat is trapped (which is caused by the greenhouse gases). That's why, on average, Earth stays at 58 degrees Fahrenheit.
Element Cr goes from Cr --> Cr³⁺
element Fe goes from Fe³⁺ --> Fe²⁺
oxidation reactions are when the species gives out electrons and its oxidation number increases.
reduction reactions are when the species take in electrons and its oxidation number reduces.
Cr : oxidation number of Cr - 0 and Cr³⁺ - +3
Theres an increase in oxidation number from 0 to +3. Therefore its an oxidation reaction. Cr gets oxidised.
Fe : oxidation number of Fe³⁺ - +3 and Fe²⁺ - +2
There's a decrease in oxidation number of Fe from +3 to +2, therefore its a reduction reaction and Fe gets reduced.
Cr reduces Fe - Cr is the reducing agent
Fe oxidises Cr - Fe is the oxidising agent