These are two questions and two answers.
Question 1: Law of Conservation of Mass
Answer: option B. The total mass remains the same during a chemical reaction.
Explanation:
The law of conservation of mass is a universal law. It states that mass is mass is neither created or destroyed, but is is conserved.
In chemical reactions, that means that, always, the total mass of the reactants equals the total mass of the products or, as the option B. states, during a chemical reaction the total mass remains the same.
Since, in chemical reactions, the atoms are not modified (the atoms just bond in different form or with different atoms), that implies that total number of each kind of atoms in the reactants equals the total number of the same kind of atoms in the products.
That is the basis for balancing the chemical equations and for the stoicheometric calculations.
Question 2 . Which element(s) are not balanced in this equation?
Answer: option A. Only the Fe is unbalanced.
Explanation:
1) Given equation: Fe₂O₃ + 3 CO → Fe + 3 CO₂
2) Count the number of atoms of each kind on each side of the equation
i) Fe
reactant side: 2
product side: 1
Therefore, Fe is not balanced
ii) O
reactant side: 3 + 3 = 6
Product side: 3 × 2 = 6
Therefore, it is balanced
iii) C
reactant side: 3
product side: 3
Therefore, C is balanced.
3) Conclusion: Only the Fe is unbalanced.
For #1, the answer is B. The total mass remains the same during a chemical reaction.
For #2, given Fe2O3 + 3CO -> Fe + 3CO2
Fe is unbalanced, and O is also unbalanced
Therefore, Option C: Fe and O are both unbalanced, is true.
Answer:
It is a hydrogen bond.
Answer:
Explanation:If you can't get a reading on a fish fossil, there are other methods you can try to determine its approximate age. Here's a step-by-step process to estimate the fossil age:
1. Relative Dating: Start by using the principles of relative dating. This method involves comparing the age of the fossil to the ages of other nearby fossils or rock layers. By studying the position of the fossil in the rock layers and the types of fossils found around it, you can make an estimate of its relative age.
2. Index Fossils: Look for index fossils, which are species that existed for a relatively short period of time but were widespread. By identifying an index fossil within the rock layers that contain the fish fossil, you can narrow down the possible time range during which the fish lived.
3. Radiometric Dating: If relative dating and index fossils don't provide a precise age estimate, you can turn to radiometric dating. This method involves measuring the decay of radioactive isotopes in the rock or fossil to determine its age. For example, you could analyze the ratio of parent isotopes to daughter isotopes in the fossil. By knowing the half-life of the radioactive isotope and the current ratio, you can calculate the approximate age.
4. Carbon-14 Dating: If the fish fossil is relatively recent (less than 50,000 years old), carbon-14 dating can be used. This method relies on the decay of carbon-14, a radioactive isotope found in living organisms. By measuring the amount of carbon-14 remaining in the fossil, you can estimate its age.
5. Other Methods: If all else fails, there are other techniques that paleontologists may use to estimate fossil age, such as studying the fossil's morphology, comparing it to known fossil records, or analyzing the chemical composition of the surrounding rocks.
Remember that estimating the age of a fossil is not always a straightforward process, and different methods can provide different ranges of accuracy. It's important to consider multiple lines of evidence and consult with experts in the field to obtain the most accurate estimate possible.
Answer: 238.6 J
Explanation:
1) Chemical energy is indicated as enthalpy
2) Energy balance:
∑ enthalpy of the reactants + energy added = ∑ enthalpy of the products + energy released.
3) ∑ enthalpy of the reactants = 85.1 J + 87.9 J = 173 J
4) energy added = 104.3 J
5) ∑ enthalpy of the products = 38.7 J + D
6) energy released = 0
7) Equation:
173J + 104.3J = 38.7 + D + 0
⇒ D = 173J + 104.3J - 38.7J = 238.6J, which is the chemical energy of the product D.
Answer:238.6 J
Explanation:
b. created models of the internal structure of atoms
c. used experiments to analyze the relationship between gas pressure and volume
d. developed practical equipment, new procedures, and methods of identifying unknown substances
To calculate this, we need the molar mass of water which is obtaine by adding the molar masses of the elements. For H2O, the molar mass is 18.02g/mol. Then, from the amount given which is 1 gram of H2O we divide the molar mass which yields to 0.06 mol of water.
(2) Stable isotopes are used as reactants.
(3) There is no chance of biological exposure.
(4) A large amount of energy is produced.