Answer:
Explanation:
<u>1) First law of thermodynamic (energy balance)</u>
- Heat released by the the hot water (345K ) = Heat absorbedby the cold water (298 K) + Heat absorbed by the calorimeter
<u>2) Energy change of each substance:</u>
Heat released or absorbed = mass × Specific heat × change in temperature
- density of water: you may take 0.997 g/ ml as an average density for the water.
- mass of water: mass = density × volume = 50.0 ml × 0.997 g/ml = 49.9 g
- Specif heat of water: 1 cal / g°C
- Heat released by the hot water:
Heat₁ = 49.9 g × 1 cal / g°C × (345 K - 317 K) = 49.9 g × 1 cal / g°C × (28K)
- Heat absorbed by the cold water:
Heat₂ = 49.9 g × 1 cal / g°C × (317 K - 298 K) = 49.9 g × 1 cal / g°C × (19K)
- Heat absorbed by the calorimeter
Heat₃ = Ccal × (317 K - 298 K) = Ccal × (19K)
<u>4) Balance</u>
49.9 g × 1 cal / g°C × (28 K) = 49.9 g × 1 cal / g°C × (19 K) + Ccal × (19 K)
Ccal = [49.9 g × 1 cal / g°C × (28 K) - 49.9 g × 1 cal / g°C × (19 K) ] / 19K
Ccal = 23.6 cal/ K
- Convert to cal / K to Joule / K
23.6 cal / K × 4.18 J / cal = 98.6 J/K
Which rounded to 2 signficant figures leads to 99 J/k, which is the first choice.
Answer:
The mass of the element is 26.20 amu
Explanation:
In this question, we are asked to calculate the mass of an element with 15 protons, 13 electrons and 11 neutrons
To calculate the atomic mass of the element, we take into consideration the masses of the individual sub atomic particles
Electrons have 0 atomic mass unit(their masses are negligible) we have no business here, Protons have a mass of
1.00727647 amu, while the mass of neutron is 1.0086654 amu
The mass of 15 protons is thus 15 * 1.00727647 = 15.10914705 amu
The mass of 11 neutrons is 11 * 1.0086654 =
11.0953194 amu
Adding this together, we have ; 11.0953194 + 15.10914705 = approximately 26.20 amu
<u>Answer:</u>
The correct answer option is a. Selenium (Se).
<u>Explanation:</u>
From the given answer options, Selenium (Se) is the only element which is a non metal.
It has the atomic number 34 with atomic weight 78.96. It is a member of the sulfur group of the non metallic elements and falls in period 4 of the Periodic table.
Selenium has non metallic properties which are intermediate between the elements that lie above and below it in the Periodic table.
Hello!
As a chemical reaction occurs and the thermometer in the container records a decrease in temperature, the statement that is true about the reaction is: <span>The reaction is endothermic because heat was taken in by the reaction.
Endothermic reactions are those that require energy in the form of heat to be completed. Technically, in these reactions, the enthalpy of the products is higher than the enthalpy of the products. The requirement of energy causes the temperature to decrease. A general expression for an endothermic reaction can be written in the following way:
A + </span>Δ → B (Where Δ means heat)
Have a nice day!
So you don't jump off a cliff thinking you could fly. Laws and Motion are heavily used in jobs and help us understand more about the mechanics of how earth's gravity operates. Imagine in the future where we could manipulate gravity? That's why we learn and study this so much.
