Answer:
Explanation:
From the given information:
The accuracy depends on the internal diameter of the cylinder. The cylinder with the least internal diameter is obviously more precise.
Let's assume 1% is the error of measurement.
Then, to measure 70 mL from 10 mL cylinder
The error = [tex]10 \times \dfrac{1}{100} \times 7[/tex]
= 0.7 mL
However; for a 100 mL cylinder, the error = 1 mL
Now,
The total volume for 10 mL = (70 + 0.7) = 70.7 mL
The total volume for 100 mL = (70 + 1 ) = 71 mL
Suppose the density (d) is same for both
Then;
the mass of 10 mL = ( d × 70.7) g
the mass pf 100 mL = (d × 71) g
Thus, the mass of 100 mL is greater than that of 10 mL.
Iron and vanadium both have the BCC crystal structure and V forms a substitutional solid solution in Fe for concentrations up to approximately 20 wt.% V at room temperature. Determine the concentration in weight percent of V that must be added to iron to yield a unit cell edge length of 0.289 nm.
Answer:
Explanation:
To find the concentration; let's first compute the average density and the average atomic weight.
For the average density [tex]\rho_{avg}[/tex]; we have:
[tex]\rho_{avg} = \dfrac{100}{ \dfrac{C_{Fe} }{\rho_{Fe}} + \dfrac{C_v}{\rho_v} }[/tex]
The average atomic weight is:
[tex]A_{avg} = \dfrac{100}{ \dfrac{C_{Fe} }{A_{Fe}} + \dfrac{C_v}{A_v} }[/tex]
So; in terms of vanadium, the Concentration of iron is:
[tex]C_{Fe} = 100 - C_v[/tex]
From a unit cell volume [tex]V_c[/tex]
[tex]V_c = \dfrac{n A_{avc}}{\rho_{avc} N_A}[/tex]
where;
[tex]N_A[/tex] = number of Avogadro constant.
SO; replacing [tex]V_c[/tex] with [tex]a^3[/tex] ; [tex]\rho_{avg}[/tex] with [tex]\dfrac{100}{ \dfrac{C_{Fe} }{\rho_{Fe}} + \dfrac{C_v}{\rho_v} }[/tex] ; [tex]A_{avg}[/tex] with [tex]\dfrac{100}{ \dfrac{C_{Fe} }{A_{Fe}} + \dfrac{C_v}{A_v} }[/tex] and
[tex]C_{Fe}[/tex] with [tex]100-C_v[/tex]
Then:
[tex]a^3 = \dfrac { n \Big (\dfrac{100}{[(100-C_v)/A_{Fe} ] + [C_v/A_v]} \Big) } {N_A\Big (\dfrac{100}{[(100-C_v)/\rho_{Fe} ] + [C_v/\rho_v]} \Big) }[/tex]
[tex]a^3 = \dfrac { n \Big (\dfrac{100 \times A_{Fe} \times A_v}{[(100-C_v)A_{v} ] + [C_v/A_Fe]} \Big) } {N_A \Big (\dfrac{100 \times \rho_{Fe} \times \rho_v }{[(100-C_v)/\rho_{v} ] + [C_v \rho_{Fe}]} \Big) }[/tex]
[tex]a^3 = \dfrac { n \Big (\dfrac{100 \times A_{Fe} \times A_v}{[(100A_{v}-C_vA_{v}) ] + [C_vA_Fe]} \Big) } {N_A \Big (\dfrac{100 \times \rho_{Fe} \times \rho_v }{[(100\rho_{v} - C_v \rho_{v}) ] + [C_v \rho_{Fe}]} \Big) }[/tex]
Replacing the values; we have:
[tex](0.289 \times 10^{-7} \ cm)^3 = \dfrac{2 \ atoms/unit \ cell}{6.023 \times 10^{23}} \dfrac{ \dfrac{100 (50.94 \g/mol) (55.84(g/mol)} { 100(50.94 \ g/mol) - C_v(50.94 \ g/mol) + C_v (55.84 \ g/mol) } }{ \dfrac{100 (7.84 \ g/cm^3) (6.0 \ g/cm^3 } { 100(6.0 \ g/cm^3) - C_v(6.0 \ g/cm^3) + C_v (7.84 \ g/cm^3) } }[/tex]
[tex]2.41 \times 10^{-23} = \dfrac{2}{6.023 \times 10^{23} } \dfrac{ \dfrac{100 *50*55.84}{100*50.94 -50.94 C_v +55.84 C_v} }{\dfrac{100 * 7.84 *6}{600-6C_v +7.84 C_v} }[/tex]
[tex]2.41 \times 10^{-23} (\dfrac{4704}{600+1.84 C_v})=3.2 \times 10^{-24} ( \dfrac{284448.96}{5094 +4.9 C_v})[/tex]
[tex]\mathbf{C_v = 9.1 \ wt\%}[/tex]
Nitrogen dioxide (NO2) is a toxic gas produced by cars and factories. If a car produces one mole of NO2 during a 10 mile drive, how many grams of nitrogen dioxide are produced?
Answer:
Explanation:
molecular weight of NO₂ is 14 + 2 x 16 = 46
So one mole of nitrogen dioxide will have mass of 46 grams .
What does not affect the strength of an electromagnet?
Answer:
Unlike a permanent magnet, an electromagnet can be turned on and off using electrical current. Many variables affect the strength of this electromagnet, and there are some variables that do not affect the strength. ... Making the nail longer will not make the magnet stronger, unless you also add more turns to the coil.
electromagnet can be turned on and off using electrical current. Many variables affect the strength of this electromagnet, and there are some variables that do not affect the strength
Joaquin tells his science class that galaxies consist of gas, dust, and many planets. What is the most important component of galaxios Joaquin is missing in his description?
astero de
comets
constellations
Stars
Answer:
the answer is asteroids!
Explanation:
Answer:
astroid
Explanation:
becaus
An unknown object has a mass of 150 grams and a volume of 5 cm3. What is the density of this
object?
Answer:
1.2 cm
Explanation:
The reason how I got my answer is by dividing 150 by 125 and that gave me 1.2 cm.
3.
What do we call materials
that let heat pass through
them easily?
Thermal conductors
Thermal insulators
Transparent
4.
Which of these is a good
thermal conductor?
Plastic
Wood
Steel
5.
Which of these is a good
thermal insulator?
Steel
Iron
Polystyrene
6.
To save on heating bills, do
you think the roof of a
building should be lined with...
a thermal conductor
a thermal insulator
nothing
7.
How does heat travel?
From cold things to hotter things
From hot things to colder things
Between things of the same temperature
Answer:
thermal conductors
steel
polystyrene
thermal insulator
between things of the same temp?
sorry to ask but if its ok with you, may i get brainly, i need to rank up all i need is two more, if not its fine. thank you and yours truly golden
In a space shuttle, the Carbon dioxide, CO2 that the crew exhales is removed from the air by a reaction within canisters of Lithium Hydroxide, LiOH. The LiOH is only 85% efficient. On average, each astronaut exhales around 20.0 mol of CO2 every day. What volume of water is produced when the CO2 reacts with the excess LiOH
Answer:
What volume of water is produced when the CO2 reacts with the excess LiOH
X = 360 mL H2O
Explanation:
CO2 (g) + 2 LiOH(s) ⇒ Li2CO3 (aq) + H2O(l)
20.0 mol excess x g
X = 360 mL H2O
x mL H20 = 20.0 mol CO2 (1 mol H2O /1 mol CO2)(18 g H2O/1 mol H2O)
(1 mL H2O /1 g H2O)
X = 360 mL H2O
explain why different objects appear to be different colors.
Answer:
Different objects appear to be different colors, because we see color by light bouncing off an object and reflecting or transmitting into our eye. The amount of light that reflects or transmits into our eye depend on the color that we will see.
Methyl salicylate is a common active ingredient in liniments such as ben-gay. It is also known as oil of wintergreen. It is made up of carbon, hydrogen, and oxygen atoms. When a sample of methyl salicylate weighing 5.287 g is burned in excess oxygen, 12.24 g of carbon dioxide and 2.505 g of water are formed. What is the simplist formula for oil of wintergreen
Answer: The empirical formula is [tex]C_3H_3O[/tex].
Explanation:
The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:
[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]
where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.
We are given:
Mass of [tex]CO_2[/tex] = 12.24 g
Mass of [tex]H_2O[/tex] = 2.505 g
Molar mass of carbon dioxide = 44 g/mol
Molar mass of water = 18 g/mol
For calculating the mass of carbon:
In 44g of carbon dioxide, 12 g of carbon is contained.
So, in 12.24 g of carbon dioxide, =[tex]\frac{12}{44}\times 12.24=3.338g[/tex] of carbon will be contained.
For calculating the mass of hydrogen:
In 18g of water, 2 g of hydrogen is contained.
So, in 2.505 g of water, =[tex]\frac{2}{18}\times 2.505=0.278g[/tex] of hydrogen will be contained.
Mass of oxygen in the compound = (5.287) - (3.338+0.278) = 1.671 g
Step 1 : convert given masses into moles.
Moles of C =[tex] \frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{3.338g}{12g/mole}=0.278moles[/tex]
Moles of H=[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.278g}{1g/mole}=0.278moles[/tex]
Moles of O=[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{1.671g}{16g/mole}=0.104moles[/tex]
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For C =[tex]\frac{0.278}{0.104}=3[/tex]
For H =[tex]\frac{0.278}{0.104}=3[/tex]
For O =[tex]\frac{0.104}{0.104}=1[/tex]
The ratio of C : H : O = 3: 3: 1
Hence the empirical formula is [tex]C_3H_3O[/tex].
If a gold ring weighs 25 grams. How much energy in Joules would it take to get it to reach its melting point if the ring starts out at 75 degrees C? (melting point is 1064 C, Cp for gold is .129 J/g-C.
Answer:
3.2 × 10³ J
Explanation:
Step 1: Given data
Mass of the gold ring (m): 25 gSpecific heat capacity of gold (Cp): 0.129 J/g.°CInitial temperature: 75 °CFinal temperature: 1064 °CStep 2: Calculate the temperature change (ΔT)
ΔT = 1064 °C - 75 °C = 989 °C
Step 3: Calculate the energy required (Q)
We will use the following expression.
Q = Cp × m × ΔT
Q = 0.129 J/g.°C × 25 g × 989 °C
Q = 3.2 × 10³ J
How many grams of Mo2(S04)3 are in 5.35X10 22 molecules of Mo2 (SO4)3?
Answer:
42.658
Explanation:
1) Avogadro's number is: N(A)=6.02*10²³
2) M of (Mo₂(SO₄)₃)=96*2+96*3=480 (gr/mol);
3) if N(A) ~ 1 mol of (Mo₂(SO₄)₃), tnen 5.35*10²² ~
(5.35*10²²)/(6.02*10²³)≈0.0888 mol of (Mo₂(SO₄)₃);
4) m(Mo₂(SO₄)₃)=M(Mo₂(SO₄)₃)*0.0888;
m((Mo₂(SO₄)₃)=480*0.0888=42.658 (gr)
how far does light travel in 3.0 days
Answer:
[tex]d=7.77\times 10^{13}\ m[/tex]
Explanation:
We know that the speed of light is equal to [tex]3\times 10^8\ m/s[/tex]
We need to find how far the light travel in 3 days.
Speed of an object is equal to distance covered divided by time taken.
Also, 1 day = 86400 s
3 days = 259200 s
So,
[tex]d=vt[/tex]
[tex]d=3\times 10^8\times 259200\\\\d=7.77\times 10^{13}\ m[/tex]
So, the light will travel [tex]7.77\times 10^{13}\ m[/tex] in 3 days.
Temperature can weather rocks because A heat can cause minerals to oxidize B. most rocks do not absorb heat evenly C. water contracts when it freezes D. rocks usually melt in the hot sun
Answer:
b
Explanation:
it is not c because water expands when it freezes.
A 2.0% (w/v) solution of sodium hydrogen citrate, Na2C6H6O7, which also contains 2.5% (w/v) of dextrose, C6H12O6, is used as an anticoagulant for blood which is to be used for transfusions. What is the molarity of the sodium hydrogen citrate in the solution
Answer:
0.0847M is molarity of sodium hydrogen citrate in the solution
Explanation:
The 2.0%(w/v) solution of sodium hydrogen citrate contains 2g of the solute in 100mL of solution. To find the molarity of the solution we need to convert the mass of solute to moles using molar mass and the mL of solution to Liters because molarity is the ratio between moles of sodium hydrogen citrate and liters of solution.
Moles Na2C6H6O7:
Molar Mass:
2Na: 2*22.99g/mol: 45.98g/mol
6C: 6*12.01g/mol: 72.01g/mol
6H: 6*1.008g/mol: 6.048g/mol
7O: 7*16g/mol: 112g/mol
45.98g/mol + 72.01g/mol + 6.048g/mol + 112g/mol = 236.038g/mol
Moles of 2g:
2g * (1mol / 236.038g) = 8.473x10⁻³ moles
Liters solution:
100mL * (1L / 1000mL) = 0.100L
Molarity:
8.473x10⁻³ moles / 0.100L =
0.0847M is molarity of sodium hydrogen citrate in the solutionAnswer:
0.085M
Explanation:
Molecular weight of sodium hydrogen citrate=236.09 g
236.09 g of Na2C6H6O7 in 1000ml= 1 M
2%= 2 g in 1 litre (1000ml)
20/236.09=0.0847 M=0.085 M
identify which element is oxidized and which element is reduced.
PLZ HELPP...
2. According to the U.S. government, 4.9 billion barrels of crude oil flowed into the Gulf of Mexico following the explosion that destroyed the Deepwater Horizon drilling rig in April 2010. Express this volume of crude oil in liters and in cubic kilometers
What mass of water in grams will fill a tank 126cm long, 47 cm wide, and 13 cm high
Answer:
Mass = 76986 g
Explanation:
Given data:
Dimensions of tank = 126 cm× 47 cm× 13 cm
Mass of water required to filled = ?
Solution:
First of all we will calculate the volume of tank which is equal to the volume of water required to fill it.
Volume = length ×height ×width
Volume = 126 cm × 13 cm× 47 cm
Volume = 76986 cm³
Mass of water:
Mass = density × volume
density of water is 1 g/cm³
Mass = 1 g/cm³× 76986 cm³
Mass = 76986 g
This diagram is attempting to compare the sizes of the four inner planets. What is wrong with this diagram?
Answer:
points
Explanation:
Answer:
Where is the diagram?
Explanation:
..........................
A tank of nitrogen has a volume of 14.0 L and a pressure of 1 atm. Find the volume of the nitrogen when its pressure is changed to 0.8 atm while the temperature is held constant .
Answer:
17.5 L
Explanation:
Step 1: Given data
Initial volume of the tank of nitrogen (V₁): 14.0 LInitial pressure of nitrogen (P₁): 1 atmFinal volume of the tank of nitrogen (V₂): ?Final pressure of nitrogen (P₂): 0.8 atmStep 2: Calculate the final volume of the nitrogen
We have a gas that undergoes a change at a constant temperature. If we assume an ideal behavior, we can calculate the final volume of the nitrogen using Boyle's law.
P₁ × V₁ = P₂ × V₂
V₂ = P₁ × V₁/P₂
V₂ = 1 atm × 14.0 L/0.8 atm = 17.5 L
model of reactants and model of products
H2CO3 → H2O + CO2
Answer:
Kindly check the picture attachment.
Explanation:
H2CO3 --------------------------> H2O + CO2
The reaction above is a decomposition reaction showing how the carbonic acid that is H2CO3 decomposed into H2O and CO2. The study of how reactants react(that is the amount in which they react) in order to form a product (and the amount of product formed) is known as the stoichiometry.
H2CO3 which is the reactant has three oxygen atoms which are all directly bonded to the carbon atom. One of the oxygen atom is bonded doubly to the carbon atom.
CO2 and H2O are the products. The CO2 is linear, O=C=O with the two oxygen atoms bonded doubly each to each carbon atoms. The H2O is bent.
A certain substance X condenses at a temperature of 123.3°C . But if a 650. g sample of X's prepared with 24.6 g of urea ((NH2)2 CO) dissolved in it, the sample is found to have a condensation point of 124.3°C instead. Calculate the molal boiling point elevation constant Kb of X.
Answer:
1.6 °C.kg/mol
Explanation:
Step 1: Calculate the molality of urea
We will use the following expression.
m = mass(urea) / molar mass(urea) × kg solvent
m = 24.6 g / 60.06 g/mol × 0.650 kg
m = 0.630 mol/kg
Step 2: Calculate the boiling point elevation of X
The boiling point elevation is a colligative property that can be calculated using the following expression.
ΔTb = 124.3 °C - 123.3 °C = 1.0 °C
Step 3: Calculate the boiling point elevation constant
We will use the following expression.
ΔTb = Kb × m
Kb = ΔTb/m
Kb = 1.0 °C/(0.630 mol/kg) = 1.6 °C.kg/mol
Which statement about Niels Bohr's atomic model is true?
O Higher orbits have lower energies.
O Each orbit has a specific energy level.
O Electrons can exist in any energy level.
O Orbits close to the nucleus have no energy.
Answer:
O Each orbit has a specific energy level.
Explanation:
Neils Bohr put forward his own model of the atom based on the quantum mechanics originally developed by Planck.
He assumed the Rutherford's model and suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus.
The orbits/energy level are the permissible through which the electrons can move through.
His concept is based the concept that the electron can move round the nucleus in certain permissible orbitss
which of these is an example of the climate of a region?
A. Dry
B. Foggy
C. Overcast
D. Sunny
its dry i think
Explanation:
it might be dry
Consider the following chemical equilibrium:
NH4SH(s) ⇌ H2SgNH3(g) Now write an equation below that shows how to calculate Kp from Kc for this reaction at an absolute temperature T. You can assume T is comfortably above room temperature. If you include any common physical constants in your equation be sure you use their standard symbols, found in the ALEKS Calculator.
Answer:
See explanation below
Explanation:
First, let's write the reaction:
NH₄SH(s) <------> H₂S(g) + NH₃(g)
The reaction is already balanced so we don't need to do anything else.
Second, let's take into account the following. The Kc expression for this reaction, only compounds in gaseous state are the only ones that contribute to the equilibrium. Solid and liquid do not contribute to the Kc expression. This is because solid and liquid have a constant concentration near to 1, so, it won't do any difference.
Knowing this, the Kc expression for this reaction is:
Kc = [H₂S] [NH₃]
Now, to calculate Kp from Kc, there's an expression that helps a lot to do this. The expression is the following:
Kp = Kc (RT)ᵃⁿ (1)
Where:
R: universal constant of gases
T: Temperature in K
ᵃⁿ = difference of the coefficients of the reaction.
This expression comes from the fact that Kp is an expression that instead of working with concentrations, it works with pressure.
If we use the ideal gas equation we have:
PV = nRT
Solving for P:
P = nRT/V and C = n/V so
P = CRT
If we now replace this, in the Kp expression of equilibrium we have:
Kp = pH₂S * pNH₃
Kp = ([H₂S]RT)¹ ([NH₃]RT)¹
Kp = (RT)¹⁺¹ ([H₂S] [NH₃])
Kp = (RT)²Kc
So finally the expression for Kp would be:
Kp = Kc (RT)²Hope this helps
In general, weathering tends to occur more rapidly in warm climates than in cool climates. How does this trend explain the effect of temperature on erosion rates?
Answer:
See explanation
Explanation:
Weathering refers to the breakdown of rocks to form soil. There are several agents of weathering.
In warmer regions, there are more vegetation and microorganisms and they increase the rate of biological weathering.
Since weathering leads to the formation of soil and the rate of weathering is greater in warmer climates, it also follows that as temperature increases and more soil is formed, erosion will happen faster at this higher temperature owing to the presence of more soil compared to colder climates.
There is a huge and direct effect of temperature on the rates of erosion.
The highest rate of weathering occurs in warm and wet climate because in warm and wet climatic regions, more rainfall occurs which increase the rate of weathering. Rainfall and temperature can affect the rate in which rock weathering occurs.
High temperatures and greater rainfall increase the rate of chemical weathering. Rocks in tropical regions exposed to abundant rainfall so we can conclude that hot temperatures weather much faster than similar rocks residing in cold, dry regions.
Learn more: https://brainly.com/question/20929061
How do molecules bond?
plz answer I will give brainliest
Answer:
Atoms with a positive charge will be attracted to negatively charged atoms to form a molecule. This bonding between atoms is the key to how molecules interact with each other. ... Other molecules interact with water, combining with the atoms to create new soluble liquids.
Draw the structure(s) of the major organic product(s) of the following reaction. 1. lithium diisopropylamide / hexane 2. 1 eq. CH3I You do not have to consider stereochemistry. Omit products derived from the acidic or basic reagent itself, e.g. HN(i-Pr)2 derived from N(i-Pr)2-. If no reaction occurs, draw the organic starting material. If substantial starting material is present at the end of the reaction, include it in the products. Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. Separate structures with signs from the drop-down menu.
Answer:
See explanation below
Explanation:
You are not providing the starting material, however, I manage to find a similar question to this, so I'm gonna use it as a basis to help you answer yours.
Now let's analyze what is happening in the reaction so we can predict the final product.
We have a ketone here, reacting at first with LDA. This is a very strong base that is commonly used in reactions with ketones and aldehydes to promove a condensation. To do this, as LDA is a strong base it will occur firts an acid base reaction, substracting the most acidic hydrogen in the molecule (Which in this case, is the Beta hydrogen of the carbonile). This will cause an enolate formation.
Then, this enolate will react with the CH3I and form a new product. The final result would be a ketone with a methyl group now attached. In the picture 2, you have the mechanism and final product.
Hope this helps
Aniline, consists of carbon, hydrogen, and nitrogen. Combustion of this yields CO2, H20, and N2 as products. If the combustion of 12.5 g of aniline yields 7.1 grams of H2O, and 1.48 grams of N2, what is its empirical formula? [HINT: write out a chemical equation, consider law of conservation of mass, and then think about what percent hydrogen is in water]
A. CHN
B. C2H4N8
C. C16H15N2
D. C20H15N31
The empirical formula : C. C₁₆H₁₅N₂
Further explanationGiven
12.5 g of aniline
7.1 grams of H2O
1.48 grams of N2
Required
The empirical formula
Solution
Reaction :
mass H in H₂O :
= 2.1/18 x 7.1 g
= 0.79
mass N = 1.48
mass C :
= 12.5 g-(mass H+mass N)
= 12.5 - (0.79+1.48)
= 10.23
Mol ratio C : H : N =
= 10.23/12 : 0.79/1 : 1.48/14
= 0.853 : 0.79 : 0.106
= 8 : 7.5 : 1
= 16 : 15 : 2
A phosphate buffer is prepared with KH2PO4 at 0.02 M and K2HPO4 at 0.03 M. What is the concentration of phosphate buffer
Answer:
0.05M is the concentration of the phosphate buffer
Explanation:
A buffer is defined as the aqueous mixture of a weak acid (KH₂PO₄) and its conjugate base (K₂HPO₄). The concentration of this buffer is the sum of the concentrations of the weak acid and the conjugate base, that is:
Concentration of phosphate buffer = 0.02M + 0.03M
=
0.05M is the concentration of the phosphate buffer
15 grams of hydrogen and 7.5 grams of oxygen were placed in a beaker. An explosion happened
inside the baker that produced water. The beaker was never opened. How many grams of water
were produced
Answer:
25.33 grams of water are produced.
Explanation:
15 g H / 1.00784* = 14.8833 moles H
7.5 g O / 15.999** = 0.468779 moles O
Ratio of Hydrogen to Oxygen in Water: 2 : 1
Oxygen: 0.468779 moles
Hydrogen (calculated based on oxygen): 0.468779 * 2 = 0.937558 moles
Water: 0.468779 + 0.937558 = 1.406337 moles
Grams of water produced:
1.406337 mol * (water molar mass)
= 1.406337 mol * [2(1.00784) + 1(15.999)]
= 1.406337 mol * (18.01468***)
= 25.3347110272 g water
Notes:
*molar mass of hydrogen
**molar mass of oxygen
***molar mass of water is actually 18.01528, so the calculation of 18.01468 is close enough
-------------------------------- Summary --------------------------------
Convert hydrogen and oxygen to moles.
Determine number of moles of water using: 2 mole hydrogen + 1 mole oxygen = 1 mole water
Convert water moles to grams.