Answer:
Lady Mary Wortley Montagu adapted "variolation" instead of "vaccination" to prevent smallpox in her children. She learned about it when she was in Constantinople (Turkey) with her husband. There, prisoners were intentionally inoculated with smallpox virus under their skin. When she saw that they didn't develop the disease and were among survivors, she inoculated smallpox virus to her children (son and daughter) as well using a needle. Later on, efforts of Edward Jenner towards vaccination were also recognized and it became a fashion to inoculate smallpox as a preventive measure.
First we must understand the balanced chemical equation:
Pb(NO3)2 + K2CrO4 ==> PbCr04 + 2KNO3
This shows us that two moles of potassium nitrate are formed from 1 mole of lead nitrate or potassium chromate solution. The next step is to find out how many moles of each reactant there are. Note the word Molar is a concentration that simply means moles per liter.
2.25L of 1.5M lead nitrate = 2.25x1.5 = 3.375 moles of lead nitrate
1.15L of 2.75M potassium chromate = 1.15x2.75 = 3.1625 moles
The important part here is to see that the number of moles of the reactants are different. We know the number of moles of products will be dependent on the number of moles of reactants, and in this case there is less potassium chromate than there is lead nitrate, so this is the limiting factor as there is a one to one relationship with both reactants. Therefore, the number of moles of potassium nitrate produced is 2 x number of moles of potassium chromate. i.e. 6.325 moles of potassium nitrate is liberated.
To work out the number of grams, we must find the molar mass (the mass of one mole) of KNO3, which is the sum of the molar mass of each of its component atoms that make up the molecule. I've looked this up as 101.1 grams per mole.
Now we simply times the molar mass by the number of moles to yield the final grams liberated: 6.325 moles x 101.1 grams/mole = 639.4 grams of potassium nitrate is liberated from this reaction.
Some abiotic factors that can limit a population are space and weather these are called limiting factors (and how much water is provided)
Explain that water moves down a water potential gradient, and the salt solution has a lower water potential than the vacuole so water leaves the vacuole through osmosis
In exam Q's key points are:
- Water potential gradient
- Higher water potential in vacuole
- Leaves through osmosis
Answer:
Coal and oil (if there are two answers)
