Answer:
D. 0.75 grams
Explanation:
The data given on the iridium 182 are;
The half life of the iridium 182, 
= 15 years
The mass of the sample of iridium, N₀ = 3 grams
The amount left, N(t) after two half lives is given as follows;
For two half lives, t = 2 ×
∴ t = 2 × 15 = 30
∴ The amount left, N(t) = 0.75 grams
From the stoichiometry of the reaction, the mass of barium nitrate produced is 54.9 g.
<h3>Stoichiometry</h3>
The term stoichiometry refers to mass - volume relationships. Stoichiometry can be used to calculate the amount, mass or volume of reactants and products from the balanced reaction equation.
The equation of the reaction is written as follows;
BaCO3 + 2HNO3 ------> Ba(NO3)2 + CO2 + H2O
Number of moles of BaCO3 = 55 g/197.34 g/mol = 0.28 moles
Number of moles of HNO3 = 26 g/63.01 g/mol = 0.41 moles
From the reaction equation;
1 mole of BaCO3 reacts with 2 moles of HNO3
0.28 moles of BaCO3 reacts with 0.28 moles × 2 moles/1 mole = 0.56 moles
There is not enough HNO3 hence it is the limiting reactant.
Number of moles of Ba(NO3)2 produced is obtained from;
2 moles of HNO3 yields 1 mole of Ba(NO3)2
0.41 moles of HNO3 yields 0.41 moles × 1 mole/2 moles
= 0.21 moles of Ba(NO3)2
Mass of Ba(NO3)2 = 0.21 moles × 261.337 g/mol = 54.9 g
Learn more about stoichiometry: brainly.com/question/9743981
Answer:
The choice of the answer is fourth option that is -61 degrees.
Therefore the temperature drop is -61°Centigrade.
Explanation:
Given:
The temperature in a town started out at 55 degrees
Start temperature = 55°Centigrade. (Initial temperature)
End of the Day = -6°Centigrade. (Final temperature)
To Find:
How far did the temperature drop?
Solution:
We will have,
Substituting the above values in it we get
Therefore the temperature drop is -61°Centigrade.
Mass of methanol (CH3OH) = 1.922 g
Change in Temperature (t) = 4.20°C
Heat capacity of the bomb plus water = 10.4 KJ/oC
The heat absorbed by the bomb and water is equal to the product of the heat capacity and the temperature change.
Let’s assume that no heat is lost to the surroundings. First, let’s calculate the heat changes in the calorimeter. This is calculated using the formula shown below:
qcal = Ccalt
Where, qcal = heat of reaction
Ccal = heat capacity of calorimeter
t = change in temperature of the sample
Now, let’s calculate qcal:
qcal = (10.4 kJ/°C)(4.20°C)
= 43.68 kJ
Always qsys = qcal + qrxn = 0,
qrxn = -43.68 kJ
The heat change of the reaction is - 43.68 kJ which is the heat released by the combustion of 1.922 g of CH3OH. Therefore, the conversion factor is:
The data on Climate change is as explained below-
Explanation:
Climate change is the ominous “hard truth” concurrently. However, it is not the first time that climate change is happening. In geological history, we find plenty of evidence of climate change.
The most important and famous of all such changes is the climate change that occurred during the Mesozoic era leading to the extinction of Dinosaurus. The reason behind these all climate changes was different. However, the climate change we are witnessing at present has something extra to all this natural stuff.
The present climate change is fuelled by anthropogenic activities at large. Large scale emission of greenhouse gases possibly from burning of fossil fuels ever since the Industrial revolutions in the late 18th century has altered the chemical composition of atmospheric gases. In addition to the use of fossil fuels other activities such as agriculture, coal-based power plants, deforestation and other such activities have been instrumental in degrading the serene balance between different atmospheric gases.
The evidence of the present climate change can be gauged in-
- The rise in global average temperature-Earth’s mean temperature has risen by around 1° C ever since the 19th century. 2017 proved to be the warmest year in the record.
- Oceans have been net absorber of the heat. This has led to the warming up of oceans. This severely hampers and impact marine flora and fauna
- Deglaciation- the increasing temperature has manifested in the form of shrinking ice-sheets. Large icebergs are calving and thus has some serious long-term impact for the sustenance of mankind.
- Rise in the mean sea level- The sea level has risen by almost 10 inches since last century. This increase is all set to increase in future thus endangering the lives and livelihood of the coastal communities.
All the leading personalities of the time including the ex-president of the US Mr Barak Obama emphasised the importance of climate change and urged the global community to tackle it at earliest. In his words, he mentioned, “No other challenge poses as great a threat to the future generation as the climate change”. In addition to Mr Obama, noted climate activist Greta Thunberg described the climate change to be the greatest crisis to the humanity that it has ever faced.
Therefore, it can be safely argued that it’s urgent to talk and act tough on climate change. Climate change has transitioned into a multi-headed monster capable enough to devastate the entire mankind. It has done this earlier and sure to carry it further on.
