I have tried usingg the molecular formula, formulas in the text book but my answers dosent match any of the multiple choice answers, can someone help?
For each of the reactions shown, calculate the mass (in grams) of the product formed when 10.7 g of the underlined reactant completely reacts. Assume that there is more than enough of the other reactant.
2K(s)+Cl_2(g) ->2K Cl(s)
2K(s)+ Br_2(l) -> 2KBr(s)
moles Cl2 = 10.7/about 71 = about 0.15
Convert moles Cl2 to moles KCl.
0.15 moles Cl2 x (2moles KCl/1 mole Cl2) = 0.15 x (2/1) = 0.30 moles.
g KCl = moles x molar mass. = about 0.30 x 74.55 = about 22.5 grams KCl.
You must go through and calculate more precisely than I. Be careful with the number of significant figures.
I obtained an exact value of
22.501 which will round to 22.5 grams to three s.f.
The KBr problem is done the same way. My number for that problem is
15.935 grams which rounds to 15.9 g to three s.f.
Thank you so much for your help, for the following question i am getting wrong answers answell. for the first one i got 42.7 and the 2nd I got 19.8. Could you help? Thank you for help in advance
4Cr(s) = 3O_2(g) -> 2Cr_2O_3(s)
2Cr(s)+O_2(g)->2SrO(s)
To calculate the mass of the product formed in each reaction, you need to use the concept of stoichiometry. Stoichiometry is the calculation of reactants and products in chemical reactions.
1. Start by balancing the chemical equation. The balanced equations for the given reactions are:
2K(s) + Cl2(g) -> 2KCl(s)
2K(s) + Br2(l) -> 2KBr(s)
2. Determine the molar mass of each reactant and product. The molar mass can be found using the periodic table. The molar mass of K is approximately 39.1 g/mol, Cl is approximately 35.5 g/mol, and Br is approximately 79.9 g/mol.
3. Convert the mass of the given reactant (10.7 g) into moles. Divide the given mass by the molar mass of the reactant. For example, for the first reaction, divide 10.7 g by the molar mass of K (39.1 g/mol) to get the number of moles of K.
4. Use the balanced equation to determine the mole ratio between the reactant and the product. The ratio is based on the coefficients in the balanced equation. In this case, the ratio is 2:2 for both reactions. This means that for every 2 moles of K, you will get 2 moles of the product.
5. Use the mole ratio to calculate the number of moles of the product. Multiply the number of moles of the reactant obtained in step 3 by the mole ratio. In this case, you will get the same number of moles of the product.
6. Convert the moles of the product back into grams. Multiply the number of moles of the product by its molar mass to get the mass in grams. For example, if you obtained 2 moles of the product, multiply it by the molar mass of KCl (approx. 74.5 g/mol) to get the mass of the product.
By following these steps, you should be able to calculate the mass of the product formed in each reaction. Make sure to double-check your calculations and consider significant figures when rounding the final answer.