A.
M = 0.125 M
V = 3.0 L
M=n/V(L) ⇒ n = 0.125 mol/L *3.0L = 0.375 mol
MM of K2SO4
K2 = 2* 39 = 78 g/mol
S= 32 g/mol
O4 = 4*16 = 64 g/mol
MM = 78g/mol + 32g/mol + 64g/mol =174 g/mol
mass = n*MM = 0.375 mol*174 g/mol = 65.25 g
b.
M= 0.015 M
V = 0.55L
n = 0.015 mol/L * 0.55L = 0.00825 mol
MM NaF
Na: 23g/mol
F: 19 g/mol
MM = 23g/mol + 19g/mol = 42g/mol
mass = n * MM = 0.00825 mol * 42g/mol = 0.3465 g
c.
n = M*V(L) = 0.350 mol/L * 0,700L = 0.245 mol
MM = 6*12 g/mol + 12*1g/mol + 6*16g/mol = 180 g/mol
mass = n*MM = 0.245 mol * 180g/mol = 44.1 g
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Answer:
10.78 → 4 significant figures, pH = 10.78 → [H⁺] = 1.66ₓ10⁻¹¹ M
6.78 → 3 significant figures, pH = 6.78 → [H⁺] = 1.66ₓ10⁻⁷ M
0.78 → 2 significant figures, pH = 0.78 → [H⁺] = 0.166 M
pH always can be expressed by at least 4 significant figures. The [H⁺], can be expressed by, at least 3 significant figures
Explanation:
Significant figures are the numbers of a measurement that have certainty plus a doubtful number (it is associated with the uncertainty in the measurement). For example, if we measure a paper with a ruler and the ruler measures up to centimeters we can say that the paper is 7.5 cm long, with which we know that the paper is 7 cm + 0.5 cm which we associate with uncertainty. In this case we talk about two significant figures. If the sheet measured 7.57 cm we would already be talking about a more precise measurement and in this case with 3 significant figures.
10.78 → 4 significant figures
6.78 → 3 significant figures
0.78 → 2 significant figures
To determine [H⁺], we apply 10^-pH
10⁻¹⁰°⁷⁸ = 1.66ₓ10⁻¹¹ M
10⁻⁶°⁷⁸ = 1.66ₓ10⁻⁷ M
10⁻⁰°⁷⁸ = 0.166 M
Answer:
Atoms will rearrange and for new substances
Explanation:
In a chemical reaction, elements combine their atoms and create new substances. For this to occur, the bonds must break and form new ones with the other atoms.
The molarity of a 27%(v/v) aqueous ethanol solution is 4.63 M
calculation
convert 27%(v/v) to fraction = 27ml/100 ml
use density to convert 27ml to grams = 27 ml x0.79 g/ml = 21.33 g
find the number of moles of C2H6O
moles = mass/molar mass of C2H6O(46.07 g/mol)
moles is therefore = 21.33 g /46.07 g/mol =0.463 moles
find the molarity = moles /volume in liters
volume in liter = 100 ml/1000 = 0.1 L
molarity is therefore = 0.463 mole/0.1 L = 4.63 M