What mass in grams of sodium hydroxide is produced if 20.0 g of sodium metal reacts with excess water according to the chemical equation?
2Na(s)+2H20(l)=2NaOH(aq)+Hs(g)
How many moles of Ag can be produced if 350. g of Cu are reacted with excess AgNO3 according to the equation?
Cu(s)+2AgNO3(aq)=2Ag(s) +Cu(NO3)2(aq)
I tried these equations but just seem to not get it right. i know i need to do train tracks (set them up), i just don't know how. help?
I have written up an example of a step by step procedure for doing this type problem. The link is below. If you have any trouble, post your question with clear explanation of what you don't understand and I can help you through.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Sure, I would be happy to help you set up the train tracks for these chemical equations and find the answers. But before we start, let's understand the problem first.
For the first question, you need to find the mass of sodium hydroxide produced when 20.0 g of sodium reacts with excess water.
For the second question, you need to determine the number of moles of silver (Ag) that can be produced when 350.0 g of copper (Cu) reacts with excess silver nitrate (AgNO3).
Now, let's set up the train tracks:
Question 1:
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
Since there is no mention of the mass of water reacting, we assume excess. So, we only need to focus on the sodium (Na).
The molar mass of sodium (Na) is 22.99 g/mol.
We have 20.0 g of sodium, so let's find the molar amount. (Use the train tracks.)
20.0 g Na × (1 mol Na / 22.99 g Na) = X mol Na
Now, from the balanced equation, we can see that the ratio between sodium (Na) and sodium hydroxide (NaOH) is 2:2 or 1:1.
So, the number of moles of sodium hydroxide produced is equal to the number of moles of sodium:
X mol NaOH.
Finally, we need to find the molar mass of sodium hydroxide (NaOH), which is 39.997 g/mol.
X mol NaOH × (39.997 g NaOH / 1 mol NaOH) = Y g NaOH
Y g NaOH is the mass of sodium hydroxide produced.
Question 2:
Cu(s) + 2AgNO3(aq) → 2Ag(s) + Cu(NO3)2(aq)
Since there is no mention of the mass of silver nitrate reacting, we assume excess. So, we only need to focus on copper (Cu).
The molar mass of copper (Cu) is 63.55 g/mol.
We have 350.0 g of copper, so let's find the molar amount. (Use the train tracks.)
350.0 g Cu × (1 mol Cu / 63.55 g Cu) = X mol Cu
From the balanced equation, we can see that the ratio between copper (Cu) and silver (Ag) is 1:2.
Therefore, the number of moles of silver (Ag) produced is half of the number of moles of copper:
X/2 mol Ag.
I hope this helps! Let me know if you have any other questions.
To solve these stoichiometry problems, you can use the following steps:
Step 1: Write and balance the given chemical equation.
For the first question: 2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)
For the second question: Cu(s) + 2AgNO3(aq) -> 2Ag(s) + Cu(NO3)2(aq)
Step 2: Determine the molar mass of the substance(s) given and the one being asked.
The molar mass of sodium hydroxide (NaOH) is:
Na: 22.99 g/mol (from the periodic table)
O: 16.00 g/mol
H: 1.01 g/mol
The molar mass of copper (Cu) is 63.55 g/mol.
The molar mass of silver (Ag) is 107.87 g/mol.
Step 3: Convert the given mass to moles.
For the first question:
20.0 g Na * (1 mol Na / 22.99 g Na) = 0.870 mol Na
For the second question:
350.0 g Cu * (1 mol Cu / 63.55 g Cu) = 5.51 mol Cu
Step 4: Use the coefficients from the balanced equation to establish mole ratios between the given reactant and the desired product.
For the first question, the mole ratio is 2 moles Na : 2 moles NaOH
For the second question, the mole ratio is 1 mole Cu : 2 moles Ag
Step 5: Use the mole ratios to convert the moles of the given substance to moles of the desired substance.
For the first question:
0.870 mol Na * (2 mol NaOH / 2 mol Na) = 0.870 mol NaOH
For the second question:
5.51 mol Cu * (2 mol Ag / 1 mol Cu) = 11.0 mol Ag
Step 6: Convert the moles of the desired substance to the requested units (grams or moles, depending on the question).
For the first question, since we already have the value in moles, we don't need to convert further.
For the second question:
11.0 mol Ag * (107.87 g Ag / 1 mol Ag) = 1,186 g Ag
So, for the first question, 20.0 g of sodium metal will produce 0.870 g of sodium hydroxide.
And for the second question, 350.0 g of copper will produce 1,186 g of silver.
To solve these problems, you can use stoichiometry, which is the calculation of amounts of reactants and products in a chemical reaction. In order to use stoichiometry, you'll need the balanced chemical equations and the molar masses of the substances involved.
Let's start with the first problem:
1. Write down the balanced chemical equation:
2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)
2. Calculate the molar mass of sodium hydroxide (NaOH):
Na = 22.99 g/mol
O = 16.00 g/mol
H = 1.01 g/mol
Molar mass of NaOH = (22.99 g/mol + 16.00 g/mol + 1.01 g/mol) = 39.00 g/mol
3. Convert the given mass of sodium metal (20.0 g) to moles:
number of moles = given mass / molar mass
number of moles of Na = 20.0 g / 22.99 g/mol = 0.8708 mol (rounded to four decimal places)
4. Use stoichiometry to find the moles of NaOH produced:
From the balanced chemical equation, we can see that 2 moles of Na produces 2 moles of NaOH.
Therefore, the number of moles of NaOH produced = 0.8708 mol * (2 mol NaOH / 2 mol Na) = 0.8708 mol
5. Convert the moles of NaOH to grams:
mass = number of moles X molar mass
mass = 0.8708 mol * 39.00 g/mol = 33.92 g (rounded to two decimal places)
Therefore, 33.92 grams of sodium hydroxide will be produced.
Now let's move on to the second problem:
1. Write down the balanced chemical equation:
Cu(s) + 2AgNO3(aq) -> 2Ag(s) + Cu(NO3)2(aq)
2. Calculate the molar mass of silver (Ag):
Ag = 107.87 g/mol
3. Convert the given mass of copper (350.0 g) to moles:
number of moles of Cu = 350.0 g / 63.55 g/mol = 5.50 mol (rounded to two decimal places)
4. Use stoichiometry to find the moles of Ag produced:
From the balanced chemical equation, we can see that 1 mole of Cu reacts with 2 moles of Ag.
Therefore, the number of moles of Ag produced = 5.50 mol * (2 mol Ag / 1 mol Cu) = 11.00 mol
5. Convert the moles of Ag to grams:
mass = number of moles X molar mass
mass = 11.00 mol * 107.87 g/mol = 1186.57 g (rounded to two decimal places)
Therefore, 1186.57 grams of silver will be produced.
Remember to always start with a balanced chemical equation and use the proper conversions to determine the answer.