Answer:
C
Explanation:
energy cannot be created or destroyed like solar energy for instance. it is already energy because it comes from the sun and for other reason.
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Answer:
Soluble salts can be made by reacting acids with soluble or insoluble reactants. Titration must be used if the reactants are soluble. Insoluble salts are made by precipitation reactions.
Making insoluble salts
An insoluble salt can be prepared by reacting two suitable solutions together to form a precipitate.
Determining suitable solutions
All nitrates and all sodium salts are soluble. This means a given precipitate XY can be produced by mixing together solutions of:
X nitrate
sodium Y
For example, to prepare a precipitate of calcium carbonate:
X = calcium and Y = carbonate
mix calcium nitrate solution and sodium carbonate solution together
calcium nitrate + sodium carbonate → sodium nitrate + calcium carbonate
Ca(NO3)2(aq) + Na2CO3(aq) → 2NaNO3(aq) + CaCO3(s)
It also works if potassium carbonate solution or ammonium carbonate solution is used instead of sodium carbonate solution. Remember that all common potassium and ammonium salts are soluble.
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Explanation:
<span>A chemist adds 155.0ml of a 4.10 X 10^-5 mmol/L of a zinc oxalate (ZnC2O4)solution to a reaction flask. Calculate the mass in micrograms of zinc oxalate the chemist has added to the flask.
1mmol = 10^-3 mol
Therefore 4.10*10^-5mmol = 4.10*10^-8mol
molar mass ZnC2O4 = 65.39+(2*12.011)+(4*15.99) = 153.372g/mol
You have 4.10*10^-8 mol/litre =153.372 * 4.10*10^-8 = 6.29*10^-6 grams / litre (* see below)
But you have 155ml. Mass of ZnC2O4 = 155/1000*6.29*10^-6 g
Mass is = 9.75*10^-7 grams
1µg = 10^-6 g
You then have 9.75*10^-7/10^-6 = 0.975µg ZnC2O4
(*see below) at this point you could have said:
1µg = 10^-6 g therefore you have a solution of 6.29µg per litre,
155ml = 6.29*155/1000 = 0.975µg ZnC2O4</span>