All categories

3 years ago

Nahco3 is the active ingredient in baking soda. how many grams of oxygen are in 0.72 g of nahco3?

1 answer:

4 0

M (O) = M x n

M (O) = 16g/mol

n (O) = 3 x n (NaHCO3)

n (NaHCO3) = m/M

m (NaHCO3) = 0.72g

M (NaHCO3) = 23 + 1 + 14 + 16 x 3 = 86g/mol

n (NaHCO3) = 0.72/86 = 0.008372mol

n (O) = 3 x 0.008372 = 0.02512

m (O) = 16 x 0.02512 = 0.402g

You might be interested in

Chem please help theres a photo attatched

a_sh-v [17]

Answer:

the top one is 100.000 and bottom one is 100.000

Explanation:

8 0

3 years ago

Read 2 more answers

Using the equations and enthalpy values provided, which mathematical expression can be used to determine the unknown enthalpy ch

vlabodo [156]

In order to solve this, we need to make use of Hess' Law.

We are already given the equations and their corresponding deltaH. Using Hess' Law, we can generate this equation:
104 kJ = x - (-1182 kJ) - (-1144 kJ)

Among the choices, the answer is
B.104 = x - [(-1182) + (-1144)]

3 0

3 years ago

Read 2 more answers

A scientist, Dr. Sigma, states that a chemical taken internally once a day will prevent the common cold. However, no other scien

pshichka [43]

Answer:

not valid

Explanation:

Expert judgment is a useful validation method to verify the reliability of an investigation that is defined as “an informed opinion of people with experience in the subject, who are recognized by others as qualified experts in it, and who can give information, evidence, judgments and assessments ”

After submitting an instrument for comparison to the consultation and expert opinion, it must meet two quality criteria: validity and reliability. The validity of content is often established based on two situations, one that concerns the design of a test and the other, the validation of an instrument subject to translation and standardization procedures to adapt it to different cultural meanings. It is here that the task of the expert becomes a fundamental task to eliminate irrelevant aspects, incorporate those that are essential and / or modify those that require it.

5 0

3 years ago

Epinephrine (adrenaline) is a hormone secreted into the bloodstream in times of stress. It contains 59.0% C, 7.15% H, 26.20% O,

vichka [17]

Answer:

C9H13O3N

Explanation:

Take the atomic mass of C=12.0, H=1.0, O=16.0 and N=14.0.

We can draw a chart (please view this on desktop so to avoid spacing errors):

Let the mass of Epinephrine be 100g.

C H O N

mass(g) : 59 7.15 26.2 7.65

no. of moles : 59/12 =4.9167 7.15/1 = 7.15 26.2/16=1.6375 7.65/14=0.5464

(n.o.m. = mass/molar mass)

Ratio: 4.9167/0.5464 =9 7.15/0.5464=13 1.6375= 3 0.5464/0.5464 =1

(divide the n.o.m. by the smallest n.o.m., which is 0.5464 in this case, take the whole numbers)

So, the empirical formula will be: C9H13O3N

But this is still not yet the molecular formula. We have to ensure the molar mass is 183g/mol. Multiply the empirical formula by n.

So, let the molecular formula of Epinephrine be (C9H13O3N)n.

12x9n + 1x13n + 16x3n + 14n = 183

108n + 13n + 48n + 14n = 183

183 n = 183.

n = 1

Hence, the molecular formula is C9H13O3N.

3 0

3 years ago

You are working in your laboratory and decide to do some cleaning. You find a test tube with some brown substance congealed at t

Anna [14]

Answer:

The mystery substance is C. Bromine (Br)

Explanation:

Argon (Ar) is a noble gas. Whose freezing point is -189 °C (very low), thus it cannot be the frozen substance. Also, it is not reactive, thus is would have not reacted with iron. Hence, argon is not the mystery substance.

Scandium (Sc) is a metal from group 3 of the periodic table, thus is will not react with iron. Thus, scandium is not the mystery substance.

Both bromine and iodine are halogens (group 17 of the periodic table).

The freezing point of bromine is −7.2 °C, and the freezing point of iodine is 113.7 °C. Thus, both could be solids (frozen) in the lab.

The reactivity of the halogens decrease from top to bottom inside the group. Bromine is above iodine. Then bromine is more reactive than iodine.

Bromine is reactive enough to react with iron. Iodine is not reactive enough to react with iron.

You can find in the internet that bromine vapour over hot iron reacts producing iron(III) bromide. Also, that bromine vapors are red-brown.

Therefore, the mystery substance is bromine (Br).

7 0

3 years ago