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3 years ago

A sample of black coffee was measured to have [h3o+] = 7.94 × 10−6. what is true about this solution?

1 answer:

6 0

Being given the hydronium (or simply the hydrogen) ion concentration (molarity), one of the easiest properties of the solution to determine is its pH. The pH of a solution indicates the acidity (or basicity) of a given solution. The typical pH range of solutions is from 1 to 14, with 7 being neutral, 1 to 6 being acidic, and 8 to 14 being basic.

To determine the pH of a solution, the negative log (-log) of the hydronium/hydrogen ion concentration (molarity) of the solution is calculated. Thus (assuming that the given hydrogen ion concentration is in molarity (mol/L)),

pH = -log( $H^{+}$ ) or -log( $H_{3} O^{+}$
pH = -log (7.94 × 10−6 mol/L)
pH = 5.13

Because the pH is less than 7 (within the range 1 to 6), then the black coffee solution is acidic.

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The solubility of N2 in blood can be a serious problem (the "bends") for divers breathing compressed air (78% N2 by volume) at d

OLga [1]

Answer:

The volume is 19.7 mL

Explanation:

Step 1: Given data

Pressure at sea level = 1.00 atm

Pressure at 50 ft = 2.47535 atm

kH for N2 in water at 25°C is 7.0 × 10−4 mol/L·atm

Molarity (M) = kH x P

Step 2: Calculate molarity

M at sea level:

M = 7.0*10^-4 * (1.00atm * 0.78) = 5.46*10^-4 mol/L

M at 50ft:

M = 7.0*10^-4 * (2.47535atm * 0.78) = 13.5*10^-4 mol/L

We should find the volume of N2. To find the volume whe have to find the number of moles first. This we calculate by calculating the difference between M at 50 ft and M at sea level.

13.5*10^-4 mol/L - 5.46*10^-4 mol/L = 8.04*10^-4 mol/L

Step 3: Calculate volume

P*V=nRT

with P = 1.00 atm

with V = TO BE DETERMINED

with n = 8.04*10^-4 mol/L *1L = 8.04*10^-4

with R= 0.0821 atm * L/ mol *K

with T = 25 °C = 273+25 = 298 Kelvin

To find the volume, we re-organize the formula to: V=nRT/P

V= (8.04*10^-4 mol * 0.0821 (atm*L)/(mol*K)* 298K ) / 1.00atm = 0.0197L = 19.7ml

The volume is 19.7 mL

5 0

3 years ago

if 100. mL of 0.800 M Na2SO4 is added to 200. mL of 1.20 M NaCl, what is the concentration of Na+ ions in the final solution? As

Black_prince [1.1K]

Compounds Na₂SO₄ and NaCl are mixed together are we are asked to find the concentration of Na⁺ in the mixture
Na₂SO₄ ---> 2 Na⁺ + SO₄³⁻

1 mol of Na₂SO₄ gives out 2 mol of Na⁺ ions

the number of Na₂SO₄ moles added - 0.800 M/1000 * 100 ml
= 0.08 mol
therefore number of Na⁺ ions from Na₂SO₄ = 0.08 * 2 = 0.16 mol

NaCl ----> Na⁺ + Cl⁻
1 mol of NaCl gives 1 mol of Na⁺ ions
number of NaCl moles added = 1.20 M/1000 * 200 ml
= 0.24 mol
number of Na⁺ ions from NaCl = 0.24 mol

total number of Na⁺ ions in the mixture = 0.16 mol + 0.24 mol = 0.4 mol
as stated the volumes are additive,
therefore total volume = 100 ml + 200 ml = 300 ml
the concentration of Na⁺ ions = number of moles / volume
= 0.4 mol/ 0.3 dm³
concentration of Na⁺ = 1.33 mol/dm³

5 0

3 years ago

PLEASE HELPPP :[

kkurt [141]

Answer:

C. The fruit and the hamburgers were affected by an increase in heat energy.

Explanation:

One claim Harvey can use to support the examples from his experiment is that the hamburgers and fruits were affected by an increase in the heat energy.

This chemical change is one that is solely driven.
This action Harvey is carrying out is cooking
When meals are cooked, the raw substances undergoes chemical change via the action of heat.

5 0

2 years ago

A container is filled with Neon gas. It has a volume of 1.5L and a pressure of 101.3 kPa. If the volume of the container is incr

Marta_Voda [28]

Answer:

37.98 kPa.

Explanation:

We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

R is the general gas constant,

T is the temperature of the gas in K.

If n and T are constant, and have different values of P and V:

(P₁V₁) = (P₂V₂)

Knowing that:

P₁ = 101.3 kPa, V₁ = 1.5 L,

P₂ = ??? kPa, V₂ = 4.0 L.

Applying in the above equation

(P₁V₁) = (P₂V₂)

∴ P₂ = (P₁V₁)/V₂ = (101.3 kPa)(1.5 L)/(4.0 L) = 37.98 kPa.

7 0

3 years ago

Thread-like structures that are found in the nucleus of a cell that contains all DNA.

lbvjy [14]

I think the awnser is C chromosomes

5 0

3 years ago